In the figure ABCD is a square and circle O
is tangent to AB, BC, CD, and AD at T_{1}, T_{2}, T_{3}, and T_{4},
respectively. F is a point on the semicircle T_{1}T_{2}T_{3}, and lines
CB and FT_{3} meet at G. If FT_{3} = a, FG = b, and S is the area of
triangle GCT_{3}, prove that S = a(a+b)/4.
