Consider a quarter of a circle of radius 25. Let r be the radius of the circle inscribed in this quarter of a circle. Find r.  Choose the correct option:
A) 16*(sqr2 -1)
B) 8*(sqr3 -1)
C) 25*(sqr2 - 1)
D) 12* (sqr7 -1)
E) None of these
I got 16/(sqr2 +1) and just forgot to multiply by (sqr2 -1).   Answer is 25*(sqr2 - 1)
<result>C</result>
Consider a quarter of a circle of radius 25. Let r be the radius of the circle inscribed in this quarter of a circle. Find r.