urgent....help needed
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hi um i have a maths exam tomorrow and i was doing this question:ok ive done the question
i worked out the are for the base and it came as 48 (6 x 8)
but when i looked in the markscheme for some reason they had multiplied it by 2....can anyone explain why????
Ah, right this is going to be hard to explain so just bare with me. 
For the surface area you have to work out the area of each face and add them together.
So, the first one would be (3x3) because the front face can be split into three squares which makes area much easier. So, each each small square is worth 9cm. You then x3 because there is 3 mini squares on the front face. So, the front face is (9+9+9) which is 27. Because it's a 3D shape you need to times 27 by 2, then you will get the back face as well. So, that's 54.
Now you've got the front and back face you need to get the side faces. These are rectangles and don't need splitting, so you work out the area of ONE rectangle. (8x3) which is 24. Then you need to count how many rectangles are on the side faces INCLUDING the ones you can't see. Which is 8, so you do (24x8) and you get 192.
Now, you add the front, back and side areas together which is (192+54) and you get 246. Sorry, if it's hard too understand and good luck for your exam tomorrow!
I have a maths one as well. D;
For the surface area you have to work out the area of each face and add them together.
So, the first one would be (3x3) because the front face can be split into three squares which makes area much easier. So, each each small square is worth 9cm. You then x3 because there is 3 mini squares on the front face. So, the front face is (9+9+9) which is 27. Because it's a 3D shape you need to times 27 by 2, then you will get the back face as well. So, that's 54.
Now you've got the front and back face you need to get the side faces. These are rectangles and don't need splitting, so you work out the area of ONE rectangle. (8x3) which is 24. Then you need to count how many rectangles are on the side faces INCLUDING the ones you can't see. Which is 8, so you do (24x8) and you get 192.
Now, you add the front, back and side areas together which is (192+54) and you get 246. Sorry, if it's hard too understand and good luck for your exam tomorrow!
I have a maths one as well. D;
Best way to do it is this:
Look at the picture and imagine that the groove part is actually pushed back out. You then have an almost complete rectangular prism with a tiny bit missing on each end. You have 4 sides each measuring 8*6, so that's 4 * 48 = 192. Then the face closest to you is 6*6 = 36 and there are two of those so thats 72. So total so far is 264. You have a quarter of each end face missing though, which is 3 * 3 = 9. 2 of those = 18. So you have 264-18 = 246 cm^2.
Look at the picture and imagine that the groove part is actually pushed back out. You then have an almost complete rectangular prism with a tiny bit missing on each end. You have 4 sides each measuring 8*6, so that's 4 * 48 = 192. Then the face closest to you is 6*6 = 36 and there are two of those so thats 72. So total so far is 264. You have a quarter of each end face missing though, which is 3 * 3 = 9. 2 of those = 18. So you have 264-18 = 246 cm^2.
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