Given triangle AED is isosceles, AD is the base of the triangle.

Given triangle AED is isosceles, AD is the base of the triangle. The outside angle at the apex D is 130 degrees. Find the interior corners of the triangle.

It is known that the sum of the outer and corresponding inner angles is 180 °. You can define the inner corner D:

D = 180 ° – 130 ° = 50 °.

It is known that in an isosceles triangle the angles at the base are equal, then we determine the angle A:

A = D = 50 °.

Knowing that in any triangle the sum of the interior angles is 180 °, we find the angle E:

E = 180 ° – 50 ° – 50 ° = 80 °.

Answer: angle A = 50 °; angle E = 80 °; angle D = 50 °.