This is an isosceles triangle because 2 of the sides are the same length (marked with single slashed through them). The Isosceles Triangle Theorem tells that if 2 sides are congruent to each other, then the angles opposite those sides are congruent to each other as well. That means that the bottom left angle measures 68. According to the Triangle Angle-Sum Theorem, all the angles of a triangle have to add up to equal 180, so:
