This is an iscoceles triangle, since the base angles are equal and the altitude bisects one of the angles. 180 - 110 = 70, meaning the angles are 70 , 70 and 2x. We know that 70 + 70 + 2x = 180 from the angle sum theorem, so 140 + 2x = 180, and 40 = 2x. x = 20°
