Here is the problem.
Consider an isoceles triangle ABC.
Please see the diagram below and IGNORE the dots which are used to show the positions of the points. Point D is a point on side AB.
......................A
.................D
..............B__________C
suppose that side AB=side AC. angle BAC=20 degrees and angle BDC= 30 degrees.
Prove that side AD=side BC.
Please help. thanks