Question

p is the exterior of circle with centre o and radius r and the tangents from p to the circle touches the circle at x and y if op=25 and py=24 then find r

Answer 1

let another secant which passes from p and center
let x and y are the intersect points 
it can be solve with a fundamental properties if circle's secant
PA*PB=PX*PY
9*13=(13-R)*(13+R)
calculate it you will find R=5