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#1 2006-12-11 09:33:29
- cat908111
- Member
- Registered: 2006-10-09
- Posts: 4
volume
i have the equation:
400=Πr²h where Π is pi
can anyone help to find r and h
thankyou
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#2 2006-12-11 09:46:53
- mathsyperson
- Moderator
- Registered: 2005-06-22
- Posts: 4,900
Re: volume
You can only find r or h in terms of h or r, as it were. If you know one, then you can work out the other, but you can't work out them both.
From 400 = πr²h, you can get r by dividing by πh:
400/πh = r²
And then square-rooting: r = √(400/πh) = 20/√(πh)
You can get h by rearranging in the same way, but without needing to square root.
Why did the vector cross the road?
It wanted to be normal.
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