Determine the angles of an isosceles triangle DEP if the outer angle of the apex angle E is 107 degrees.

1. Since the outer corner at the vertex is adjacent to the inner one, let us determine its value.

180 – 107 = 73 °.

2. From the condition of the problem, the triangle is isosceles, that is, the degree measure of the angles at the base is the same. Let’s find these corners.

(180 – 73) / 2 = 107/2 = 53.5 °.

Answer: The angles are 73 °, 53.5 ° and 53.5 °.