The Quadrilateral OABC is evidently a square as
1. OA = OC
2. /_AOC is 90deg.
3. /_OAB is 90deg. as tangent is perpendicular to radius (as percieved from figure)
So statement A gives the value of pi*(360-90)/360*r, from which r can be calculated
Statement B gives the perimieter of the square which is 4r so r can be calculated
Both are independently sufficient
When you feel like giving up, remember why you held on for so long in the first place.