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As Maths Differentiation

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Reply 20
Avatar for Nelson199
Nelson199
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Original post by loperdoper
Yep, that's exactly what you need to do.

Am i correct to say that you can rearrange it to say 2piR = 1000r^2
Then 2pi/1000 = r^2/r



(or
Reply 21
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Nelson199
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Original post by loperdoper
Yep, that's exactly what you need to do.

This becomes r^2/r = 2Pi/1000?
Original post by Nelson199
This becomes r^2/r = 2Pi/1000?


Careful - you've made a mistake in your working.
Reply 23
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Nelson199
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Original post by loperdoper
Careful - you've made a mistake in your working.

Ah damn. should it have been r^2 x r = 1000/2pi
Original post by Nelson199
Ah damn. should it have been r^2 x r = 1000/2pi


Yeah, and do you see the final stage? It's really just clearing up the left side so that it clearly goes r=[ans]
Reply 25
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Nelson199
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Original post by loperdoper
Yeah, and do you see the final stage? It's really just clearing up the left side so that it clearly goes r=[ans]

do you just square root the right hand side twice to get the answer
I got r to be 5.42??
Original post by Nelson199
do you just square root the right hand side twice to get the answer


Almost - r×r2=r3r \times r^2 = r^3 so you cube-root your answer.
Square rooting twice gives you an entirely different, incorrect answer.

What do you come out with?
Original post by GrandMasti
I got r to be 5.42??


That was what I got as well.
Reply 29
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Nelson199
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yeah sorry miss read my calculator aha r^3 is what i got so i cube rooted the right hand side
Original post by Nelson199
yeah sorry miss read my calculator aha r^3 is what i got so i cube rooted the right hand side


And hopefully you got ~5.42?

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