Let ABC be a triangle and AB=AC . D is a point on BC such that BA \equal{} BD and B is between C and D . Let Ic be center of the circle which touches AB and the extensions of AC and BC . CIc intersect the circumcircle of ABC again at T .
If \angle TDI_{c} \equal{} \frac {\angle B \plus{} \angle C}{4} then find ∠A geometrycircumcircleincenterratiotrigonometrycyclic quadrilateralgeometry proposed