12.1 MATH

A tessellation is a pattern made of identical shapes. You can make your own tessellation by fitting copies of a shape together, without gaps or overlaps. You say the shape tessellates, or is a tessellating shape.

Here are some examples of shapes that tessellate with themselves and not with them self=


When you make a tessellation are made by repeating a shape and using half-turn rotations of the same shape. For examples, this triangleand a half-turn rotation of the same trianglefit together exactly to make a tessellation like this. 
In any tessellation, the sum of the angles at the point where the vertices of the shape is 360°

12.4 MATH

When you enlarge a shape, all the lengths of the shape increase in the same proportion. This is called a scale factor. All the angles in the shape must stay the same.

When you describe an enlargement you must give:

-scale factor of the enlargement

-position of the centre of enlargement

Clean Water Shortage -Another group assignment / SOSE&ENGLISH&TEAMWORK

A shout for a help from Indonesia

As one of the least clean water supplied province, Papua -Bovendigoel surely needs a help from us Indonesians as it is part of our country too. The clean water supply in Papua is surely low in many areas. As having clean water only twice a week in which defines it is lack of clean and hygienic water. Us PTW.org (short for Pure The Water organisation) are here to start a help for our brothers and sisters in Papua.

Our aim is to help the people of Papua -Bovendigoel as they are one of the least clean water supplied region as well as helping improve their environment. Many may have been a victim of the disease that they consume of contaminated water that they take without any warning. And this is also a big cause of their death. To solve this problem is to pure the water. And our solution is exactly what the previous sentence have said, we use PureIt by Unilever Indonesia to help pure the water.

As we know that the cost of PureIt is not as cheap as buying a water bottle, there is a high possibility for us to ask you to help too by donating some funds or even better, donating some PureIt to help more people and more children in the Papua Bovendigoel. We would also like to ask help from the original company of PureIt which is Unilever to give a hand to ease this process of helping them.

At the time that when this problem will hopefully one day soon to be solved, many lives will hold on and families won't have to worry for water supply because water for them will be like for us -it will only be a tap away. And we can give them a better chance of a better and brighter future. There are so much that have suffered this and none of us really notice but expectantly, you will notice and help.

Let's all open our eyes and focus our hearing for there is a shout from Papua, a part of Indonesia that is asking for our help.

-PTW.org

By: Zahra, Raissa, Atifa, Kyla, Tsamara -Students of Al-Taqwa College Indonesia

Letter for the up coming president (english project)

Assalamualikum wr wb.

  Dear Jokowi,

As the upcoming president of this country, Indonesia, i would like to request some models of deduction. As you know, this beautiful country of  ours ha too many imperfection that could be easily changed. 

Here are some the ideas i would like to talk about: 

• As you know, our neighboring country Singapore has high taxes, so should we with the higher tax we could have more clean water or a cleaner city.
• With, higher tax public transportation could be more save and possible. If you think it over it could be more help full for the environment. By allowing many people to ride an one bus instead of many car being used.
• I cant make up my mind about whether  more job opportunities should be opened up for people living below poverty, or that foundation should open up to provide for poor people.
• As with the rate of population in Jakarta we should talk it over with others about how the rules should be changed so that people will obey the more strict rules.
• The traffic wont go away bye it self need to be a huge change in the law of selling auto cars, such as for example, such as one family should have one car or for more cars they should be proper certificate. 

In  closed with this letter, i hereby state that there are many things that you as the up coming president could try to do or change, because this country has large population. 

wassalamualikum wr wb. 

Made by : Atifa Anuz and Kyla Aulia :) year 9 

IT project

TCP / IP 

Definition: Transmission Control Protocol (TCP) and Internet Protocol (IP) are two distinct network protocols, technically speaking. TCP and IP are so commonly used together, however, that TCP/IP has become standard terminology to refer to either or both of the protocols.

IP corresponds to the Network layer (Layer 3) in the OSI model, whereas TCP corresponds to the Transport layer (Layer 4) in OSI. In other words, the term TCP/IP refers to network communications where the TCP transport is used to deliver data across IP networks.

The average person on the Internet works in a predominately TCP/IP environment. Web browsers, for example, use TCP/IP to communicate with Web servers.

used to connect hosts on the Internet. TCP/IP uses severalprotocols, the two main ones being TCP and IP. TCP/IP is built into the UNIX operating system and is used by the Internet, making it the de facto standard for transmitting data over networks. Evennetwork operating systems that have their own protocols, such asNetware, also supportTCP/IP. 

Resource usage

Most implementations allocate an entry in a table that maps a session to a running operating system process. Because TCP packets do not include a session identifier, both endpoints identify the session using the client's address and port. Whenever a packet is received, the TCP implementation must perform a lookup on this table to find the destination process. Each entry in the table is known as a Transmission Control Block or TCB. It contains information about the endpoints (IP and port), status of the connection, running data about the packets that are being exchanged and buffers for sending and receiving data.

The number of sessions in the server side is limited only by memory and can grow as new connections arrive, but the client must allocate a random port before sending the first SYN to the server. This port remains allocated during the whole conversation, and effectively limits the number of outgoing connections from each of the client's IP addresses. If an application fails to properly close unrequired connections, a client can run out of resources and become unable to establish new TCP connections, even from other applications.

Both endpoints must also allocate space for unacknowledged packets and received (but unread) data.

Data transfer

There are a few key features that set TCP apart from User Datagram Protocol:

• Ordered data transfer — the destination host rearranges according to sequence number
• Retransmission of lost packets — any cumulative stream not acknowledged is retransmitted
• Error-free data transfer
• Flow control — limits the rate a sender transfers data to guarantee reliable delivery. The receiver continually hints the sender on how much data can be received (controlled by the sliding window). When the receiving host's buffer fills, the next acknowledgment contains a 0 in the window size, to stop transfer and allow the data in the buffer to be processed.
• Congestion control 

Reliable transmission

TCP uses a sequence number to identify each byte of data. The sequence number identifies the order of the bytes sent from each computer so that the data can be reconstructed in order, regardless of any fragmentation, disordering, or packet loss that may occur during transmission. For every payload byte transmitted, the sequence number must be incremented. In the first two steps of the 3-way handshake, both computers exchange an initial sequence number (ISN). This number can be arbitrary, and should in fact be unpredictable to defend against TCP sequence prediction attacks.

TCP primarily uses a cumulative acknowledgment scheme, where the receiver sends an acknowledgment signifying that the receiver has received all data preceding the acknowledged sequence number. The sender sets the sequence number field to the sequence number of the first payload byte in the segment's data field, and the receiver sends an acknowledgment specifying the sequence number of the next byte they expect to receive. For example, if a sending computer sends a packet containing four payload bytes with a sequence number field of 100, then the sequence numbers of the four payload bytes are 100, 101, 102 and 103. When this packet arrives at the receiving computer, it would send back an acknowledgment number of 104 since that is the sequence number of the next byte it expects to receive in the next packet.

Also Known As: Transmission Control Protocol / Internet Protocol

WAN TECHNOLOGY 

WANs are all about exchanging information across wide geographic areas. They are also, as you can probably gather from reading about the Internet, about scalability—the ability to grow to accommodate the number of users on the network, as well as to accommodate the demands those users place on network facilities. Although the nature of a WAN—a network reliant on communications for covering sometimes vast distances—generally dictates slower throughput, longer delays, and a greater number of errors than typically occur on a LAN, a WAN is also the fastest, most effective means of transferring computer-based information currently available.

Circuit Switching

Circuit switching involves creating a direct physical connection between sender and receiver, a connection that lasts as long as the two parties need to communicate. In order for this to happen, of course, the connection must be set up before any communication can occur. Once the connection is made, however, the sender and receiver can count on "owning" the bandwidth allotted to them for as long as they remain connected.

Although both the sender and receiver must abide by the same data transfer speed, circuit switching does allow for a fixed (and rapid) rate of transmission. The primary drawback to circuit switching is the fact that any unused bandwidth remains exactly that: unused. Because the connection is reserved only for the two communicating parties, that unused bandwidth cannot be "borrowed" for any other transmission.

The most common form of circuit switching happens in that most familiar of networks, the telephone system, but circuit switching is also used in some networks. Currently available ISDN lines, also known as narrowband ISDN, and the form of T1 known as switched T1 are both examples of circuit-switched communications technologies.

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Message Switching

Unlike circuit switching, message switching does not involve a direct physical connection between sender and receiver. When a network relies on message switching, the sender can fire off a transmission—after addressing it appropriately—whenever it wants. That message is then routed through intermediate stations or, possibly, to a central network computer. Along the way, each intermediary accepts the entire message, scrutinizes the address, and then forwards the message to the next party, which can be another intermediary or the destination node.

What's especially notable about message-switching networks, and indeed happens to be one of their defining features, is that the intermediaries aren't required to forward messages immediately. Instead, they can hold messages before sending them on to their next destination. This is one of the advantages of message switching. Because the intermediate stations can wait for an opportunity to transmit, the network can avoid, or at least reduce, heavy traffic periods, and it has some control over the efficient use of communication lines.

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Examples ofWide Area Network Technologies

Examples of Wide Area Network Technologies Created by Edraw!
Wide Area Network	Cisco WAN Network	WAN Topology

Virtual private network (VPN) is a tecnology widely used in a public switched network (PSTN) to provide private and secured WAN for an organization. VPN uses encryption and other techniques to make it appear that the organisation has a dedicated network, while making use of the shared infrastructure of the WAN.

WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer. Key technologies often found in WANs include SONET, Frame Relay, X.25, ATM and PPP.

• ATM: A dedicated-connection switching technology that organizes digital data into 53-byte cell units. Individually, a cell is processed asynchronously relative to other related cells and is queued before being multiplexed over the transmission path. Speeds on ATM networks can reach 10 Gbps.
• Frame Relay: (FR). A high-speed packet-switched data communications service, similar to X.25. Frame relay is widely used for LAN-to-LAN interconnect services, and is well suited to the bursty demands of LAN environments.
• SONET/SDH: Synchronous Optical Network is an international standard for high speed communication over fiber-optic networks. The SONET establishes Optical Carrier (OC) levels from 51.8 Mbps to 10 Gbps (OC-192) or even higher. Synchronous Digital Hierarchy (SDH) is a European equivalent of SONET.
• X.25: The X.25 protocol allows computers on different public networks to communicate through an intermediary computer at the network layer level.
• PPP: A point-to-point link provides a single, pre-established WAN communications path from the customer premises through a carrier network, such as a telephone company, to a remote network. Point-to-point lines are usually leased from a carrier and thus are often called leased lines. For a point-to-point line, the carrier allocates pairs of wire and facility hardware to your line only.

IP can also be considered as a WAN technology in the packet switching environment.

Symbols of Network Architecture

Some network mapping symbols for network engineer. Provide a Common Graphics Technology for Network Mapping.

DNS

The Domain Name System (DNS) is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. Most prominently, it translates easily memorizeddomain names to the numerical IP addresses needed for the purpose of locating computer services and devices worldwide. The Domain Name System is an essential component of the functionality of the Internet.

An often-used analogy to explain the Domain Name System is that it serves as the phone book for the Internet by translating human-friendly computer hostnamesinto IP addresses. For example, the domain name www.example.com translates to the addresses 93.184.216.119 (IPv4) and 2606:2800:220:6d:26bf:1447:1097:aa7 (IPv6). Unlike a phone book, the DNS can be quickly updated, allowing a service's location on the network to change without affecting the end users, who continue to use the same host name. Users take advantage of this when they use meaningful Uniform Resource Locators(URLs), and e-mail addresses without having to know how the computer actually locates the services.

The Domain Name System distributes the responsibility of assigning domain names and mapping those names to IP addresses by designating authoritative name servers for each domain. Authoritative name servers are assigned to be responsible for their supported domains, and may delegate authority over subdomains to other name servers. This mechanism provides distributed and fault tolerant service and was designed to avoid the need for a single central database.

The Domain Name System also specifies the technical functionality of this database service. It defines the DNS protocol, a detailed specification of the data structures and data communication exchanges used in DNS, as part of the Internet Protocol Suite.

The Internet maintains two principal namespaces, the domain name hierarchy and the Internet Protocol (IP) address spaces. The Domain Name System maintains the domain name hierarchy and provides translation services between it and the address spaces. Internet name servers and a communication protocol implement the Domain Name System. A DNS name server is a server that stores the DNS records for a domain name, such as address (A or AAAA) records, name server (NS) records, and mail exchanger (MX) records (see also list of DNS record types); a DNS name server responds with answers to queries against its database.

resources: http://compnetworking.about.com/cs/basictcpip/g/bldef_tcpip.htm , http://www.webopedia.com/TERM/T/TCP_IP.html , http://en.wikipedia.org/wiki/Transmission_Control_Protocol , http://technet.microsoft.com/en-us/library/bb962087.aspx , http://www.edrawsoft.com/Wide-Area-Network.php , http://en.wikipedia.org/wiki/Domain_Name_System

math CHAPTER 11

CHAPTER 11 PERCENTAGES

·      11.1 à some percentages are easy to find because they are simple fractions. they are example of these on the first page of this unit, you can use the easy ones to work out more complicated percentages. You can often do this quite easily. You do not always need a calculator.

·      Example:

Ø there are 4600 people in a stadium. 58% are males. How many is that ?

100%=4600

58%= 50%+10%-2%--> these all the easy percentages to find.

50%=2300à 50%=1/2

10%=460à1/10 is easy. Just divide by 10

1%46àdivide 10% by 10 to find 1

58%= 2300+460-(2x46)= 2668 à do this sum in your head / on your paper.

Otherà you could have found 50%+5%+3%. Is that easier? J

Ø 90% of 320=?--> 320-3.2= 316.8

Ø show that 20% of 45 is the same as 45% of 20.

  So,   and     the result both of them are same.

·        11.2 à you will often need to compare groups that are different sizes. Suppose that, in one school, 85 students took an exam and 59 passed. In another school, 273 students took an exam and 147 passed. Which school did better? It’s hard to say because each school had a different number of students. The worked example shows how to use percentages to help to answer question like this.

·      Example:

Ø    In school A, 85 students took a mathematics exam and 59 passed.in school B 237 students took a mathematics exam and 147 passed. Which school had better pass rate?

59 out of 85 = 59 ÷ 85 = 69%  à  59 ÷ 85 = 0,694... =69% to the nearset whole number.

147 out of 237 = 147 ÷ 237 = 62%  à 147 ÷ 237 = 0,620.. =62%  to the nearset whole number.

The pass rate in school B is better by seven percentages points. à the difference between 62% and 69% is given on ‘percentages points.’

·       11.3 you can use percentages to describe a change in a quality. It could be an increase or a decrease. a percentages change is always calculated as apercentages f the initial value. The initial value is 100%. It is impothant to choose the correct value to be 100%

Topology of Network

Network topology is the arrangement of the various elements (links, nodes, etc.) of a computer network. Essentially, it is the topological structure of a network, and may be depicted physically or logically. Physical topology refers to the placement of the network's various components, including device location and cable installation, while logical topologyshows how data flows within a network, regardless of its physical design. Distances between nodes, physical interconnections, transmission rates, and/or signal types may differ between two networks, yet their topologies may be identical.
A good example is a local area network (LAN): Any given node in the LAN has one or more physical links to other devices in the network; graphically mapping these links results in a geometric shape that can be used to describe the physical topology of the network. Conversely, mapping the data flow between the components determines the logical topology of the network.

Diagram	Kind of Topology	Description, Advantages, and Disadvantages
	Ring	Description: Devices are connected from one to another to form a ring shape. Each host is connected to the next and the last node is connected to the first. A data token1 is used to grant permission for each computer to communicate. Advantages: Easy to install and wire. Because every computer is given equal access to the token, no one computer can monopolize the network. Disadvantages: Requires more cable than a bus topology. If one computer fails it can affect the whole network. It is difficult to identify the problem if the entire network shuts down.
	Bus	Description: All hosts are connected to the backbone cable in a linear2 fashion. Advantages: Easy to connect a computer or peripheral. Requires less cable length than a star topology. Disadvantages: If there is a break in the backbone cable, the entire network shuts down. Both ends of the backbone cable require terminators. It is difficult to identify the problem if the entire network shuts down.
	Star	Description: All hosts are connected to a single point of concentration. Usually uses a hub3 or switch4 as a center node. Range limits are about 100 meters from the hub Data on a star network passes through the hub or concentrator before continuing to its destination. Advantages: It is easy to modify and add new computers to a star network without disturbing the rest of the network. If one node or workstation (beside the middle node) goes down, the rest of the network will still be functional. The center of a star network is a good place to figure out where the network faults are located. You can use several cable types in the same network if the hub you have can handle multiple cable types. Disadvantages: Requires more cable than a bus topology. If the middle node goes down , then the entire network goes down. It is more expensive than because all cables must be connected to one central point.
	Mesh	Description: Each host is connected to all the other hosts. Advantages: Increased reliability since there are multiple paths for each node to take. Increased speed since shortcuts have been created by add more cables/links. Disadvantages: The cost of cabling all the hosts together is expensive and time consuming.

more deep explanation of some like up diagram :) 

Bus Topology

Bus networks (not to be confused with the system bus of a computer) use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message.Ethernet bus topologies are relatively easy to install and don't require much cabling compared to the alternatives. 10Base-2 ("ThinNet") and 10Base-5 ("ThickNet") both were popular Ethernet cabling options many years ago for bus topologies. However, bus networks work best with a limited number of devices. If more than a few dozen computers are added to a network bus, performance problems will likely result. In addition, if the backbone cable fails, the entire network effectively becomes unusable.

Ring Topology

In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise"). A failure in any cable or device breaks the loop and can take down the entire network.

Star Topology

Many home networks use the star topology. A star network features a central connection point called a "hub node" that may be a network hub, switch or router. Devices typically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet.
Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computer's network access and not the entire LAN. (If the hub fails, however, the entire network also fails.)



RESOURCES : http://www.sis.pitt.edu/~icucart/networking_basics/networking_topology.html , http://en.wikipedia.org/wiki/Network_topology , https://www.google.com/search?output=search&sclient=psy-ab&q=type+of+topology&btnK= , http://compnetworking.about.com/od/networkdesign/a/topologies.htm , http://whatis.techtarget.com/definition/network-topology