Posted by Loki on .
How do you solve for r, please show steps
(r2)^2 + (8  r)^2 = (r + 2)^2

Math 
Reiny,
expand, simplify, then write it in standard form
r^2  4r + 4 + 64  16r + r^2 = r^2 + 4r + 4
r^2 24r +64 = 0
solving by completing the square, easiest way in this case.
r^2  24r + 144 = 144  64
(r12)^2 = 80
r12 = ±√80
r = 12 ± 4√5