SOLUTION: {{{160 = Pi r Sqrt(36 + r^2)}}} Solve for "r" What I got up to: 160/Pi r = Sqrt(36 + r^2) (160^2)/(Pi^2 r^2) = 36 + r^2 36= ((160^2)/(Pi^2 r^2)) - r^2

Algebra ->  Radicals -> SOLUTION: {{{160 = Pi r Sqrt(36 + r^2)}}} Solve for "r" What I got up to: 160/Pi r = Sqrt(36 + r^2) (160^2)/(Pi^2 r^2) = 36 + r^2 36= ((160^2)/(Pi^2 r^2)) - r^2      Log On


   

Question 843034: 160+=+Pi+r+Sqrt%2836+%2B+r%5E2%29
Solve for "r"
What I got up to:
160/Pi r = Sqrt(36 + r^2)
(160^2)/(Pi^2 r^2) = 36 + r^2
36= ((160^2)/(Pi^2 r^2)) - r^2
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Isolate r and any expressions with it onto one side; usually the simplest.

160+=+Pi+%2Ar%2A+Sqrt%2836+%2B+r%5E2%29
160%2Fpi=r%2Asqrt%2836%2Br%5E2%29
%28160%2Fpi%29%5E2=r%5E2%2836%2Br%5E2%29
36r%5E2%2Br%5E4=%28160%2Fpi%29%5E2
r%5E4%2B36r%5E2-%28160%2Fpi%29%5E2=0 ----- this is in quadratic form, and you need to first solve for r%5E2.

Let u=r%5E2
Let
u%5E2%2B36u-%28160%2Fpi%29%5E2
-
highlight%28u=%28-36%2B-+sqrt%281296%2B102400%2F%28pi%5E2%29%29%29%2F%282%29%29 ----which part way to the answer.

which you still want to try to simplify.