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# Circle equation q watch

1. The diameter of this circle is (root)85, so the radius is 1/2 of (root)85. Why can it be written as (root)(85/4)?, I don't understand where the 4 is from?
2. 2= root 4
3. (Original post by Magenta96)
The diameter of this circle is (root)85, so the radius is 1/2 of (root)85. Why can it be written as (root)(85/4)?, I don't understand where the 4 is from?
(just in case you haven't replied because you weren't quoted earlier )
4. Oh right, I understand now, thank you for the answers and PhysicsGal for quoting me above!

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Updated: April 6, 2013
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