Learn AREA AND PERIMETER. thetransfertutor.com

Transcription

1 AREA AND PERIMETER

2 Area and Perimeter These two topics are a bit like second cousins, and they can be every bit as annoying. In fact they can be like second cousins who are twins and who wear the same outfits to your house every Christmas. Not as annoying as Jedward, but a close second. The important thing to remember is not to confuse them. When you see a question that looks like it could be a perimeter or area question read the question carefully to see which category it falls into. There may possibly be a question which asks both, we ll practise for these but generally it will be one or the other. Ok enough about those annoying cousins let s see what we need to know.

3 Perimeter Simply put this is the distance around an object. Think football fields, your playground, using a trundle wheel on a cold January morning counting clicks!!! First we need to find the length of each side by Counting the squares. 8 cm 6 cm 6 cm 8 cm The perimeter of the shape is = 28cm. Mark where you are to start As you count the sides write the lengths in the form of a sum Add up the lengths carefully Check the answer to make sure it is the correct form of units: cm, mm etc.

4 AREA Area is the space inside a shape or object. Think back to colouring in squares in a Maths workbook, this is area. There are a few different ways that an exam can test area. This is the first. To find out how much shape is inside we can Count the squares. The area of the shape is 18cm 2. AREA is the space inside!! Tick each square as count. Add up the ticks Check once before moving on That s it. That s area taken care of. Now if only life was that simple.

5 The second type of question involves irregular shapes. In these questions there isn t an exact answer. The person who will mark your test will be given a range of answers from which they can give a mark. So if you follow the correct method you will get the mark. This is an irregular shape. This means that the sides aren t straight. Look out for the word estimate: this means there is a range I would recommend starting in the top left hand corner and work across from left to right. If a square is half or more tick it. Work across the row. Then move down to the next row and continue as before. Now go back and count the ticks carefully. Check once before moving on.

6 This needs to be practised quite a few times to ensure you understand how to do these problems effectively. Area simply is the amount of space that a 2-d object takes up. You can be 99% sure that an area question will rear its head in a test so it s really important to make sure you can calculate areas. This is an examiners favourite. We can work out the area of a rectangle Using the formula Length Breadth Length Width Area = length x width Write the equation length times breadth= area Then fill in the relevant measurements from the digram you are given

7 Simply multiply the length by the breadth Check your answer to see if the examiner wants it changed to a different unit Remember the answer to a squared calculation must contain the squared symbol. You will most likely be given it but in the case of anyone taking the AQE tests make sure that if it isn t there write it in. The formula can be re-arranged if you know the area Length = Area width Width = Area length I m not sure, but I would say that the people who make up the tests must like gardening in their spare time. This is another firm favourite of theirs. You have to find the area of the path. Mmmm, just had a lovely idea for those tests in November!!!!

8 Don t worry they didn t bet on the transfertutor being around to thwart their cunning plans!!! Area of a Border = Total Area Inside Area 6m 1m Total area = 12m x 6m = 72m 2 Inside area = 4m x 10m = 40m 2 Border = 72m 2 40m 2 = 32m 2 12 To find the inside rectangle s dimension subtract 2 off the length and 2 off the breadth of the larger square. Ok these are probably the trickiest. We call these compound shapes. Compound words are called compound words because they are made from two words. In the same way compound shapes are made from two shapes. To work out the total area of compound shapes you must split the shape into 2 parts or even three parts. We then find the area of each of the three shapes and then add them back together. Simple isn t it??

9 5cm Total area = = 100cm 2 2cm 12cm Area = 5 x 12 4cm Area = 60cm 2 4 x cm 2 10cm To find the area of this shape we have to split it up into two rectangles. 9cm A shape that is made from other shapes is known as a compound shape.

10 4cm 9cm Area = 4x 9 36cm 2 2cm 4cm 4cm 5cm Area = 4 x 5 20cm 2 2cm 4cm Total area = = 56 cm 2 If faced with a compound shape First divide the shape with a line Next take the first shape and find its length and breadth Multiply and find the area Now do the same for the other shape Add the two calculations together Check your unit of measurement I personally find that with these types of area questions you need to complete of them before you really get to grips with them. Ok what are you waiting for????????????????????????????