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# C2 question

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1. https://gyazo.com/9c618f6e7830c2a87fd865258b272ea3

Can someone give some assistance with part B please?? Thanks
2. iMacJack
Each unit on the axis is worth 8cm. You are multiplying both axis by each other in order to find the area R. Therefore if you multiply the area R by 64 (8 squared) then you will get the area in cm. Then its just a simple case of multiplying the area by the depth to get the volume
3. (Original post by Snasher350)
iMacJack
Each unit on the axis is worth 8cm. You are multiplying both axis by each other in order to find the area R. Therefore if you multiply the area R by 64 (8 squared) then you will get the area in cm. Then its just a simple case of multiplying the area by the depth to get the volume
Why 64? I don't understand why you times it by 8^2?
4. (Original post by iMacJack)
Why 64? I don't understand why you times it by 8^2?
It says that 1 unit is 8cm
And cross section=length*width
So you need to do 8*8=64(both axis)
Then you multiply it by whatever you got in part a and then by the height/thickness of 2
5. (Original post by 4nonymous)
It says that 1 unit is 8cm
And cross section=length*width
So you need to do 8*8=64(both axis)
Then you multiply it by whatever you got in part a and then by the height/thickness of 2
But on the X axis surely there's two units?
6. (Original post by iMacJack)
Why 64? I don't understand why you times it by 8^2?
Say if you had a rectangle which was 5 units high and 7 units wide. Then obviously A (area) would equal 35. A = 5 units x 7 units = 35 units squared

But now if we want the area in cm and we are told that 1 unit = 8 cm
We could do this : 5 x 8 = 40 cm high and 7 x 8 = 56 cm wide

Therefore are new area would equal 2240 cm squared.

In the case of the integration it is much easier to just multiply the answer for R by 8 squared. And we can do this since (using the example above)
(5x8) x (7x8) = 5 x 7 x 64
7. (Original post by iMacJack)
But on the X axis surely there's two units?
Yes but you're already taking that into account by using the answer from part a which uses the 2 in the trapezium rule. You are then multiplying this by 8 because each unit is 8cm. And then by 8 again for the other axis
8. (Original post by Snasher350)
Say if you had a rectangle which was 5 units high and 7 units wide. Then obviously A (area) would equal 35. A = 5 units x 7 units = 35 units squared

But now if we want the area in cm and we are told that 1 unit = 8 cm
We could do this : 5 x 8 = 40 cm high and 7 x 8 = 56 cm wide

Therefore are new area would equal 2240 cm squared.

In the case of the integration it is much easier to just multiply the answer for R by 8 squared. And we can do this since (using the example above)
(5x8) x (7x8) = 5 x 7 x 64
But on the x axis there is two units?
9. (Original post by 4nonymous)
Yes but you're already taking that into account by using the answer from part a which uses the 2 in the trapezium rule. You are then multiplying this by 8 because each unit is 8cm. And then by 8 again for the other axis
Ohhhhhhhhh.. okay... I see!! Thank you
10. (Original post by iMacJack)
Ohhhhhhhhh.. okay... I see!! Thank you
No problem that was a nice question for me to have a try at too so thanks. And good luck with the exam
11. (Original post by 4nonymous)
No problem that was a nice question for me to have a try at too so thanks. And good luck with the exam
You too - best of luck

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