Angle A = 50 degrees Angle C = 130 degrees AB = CB find unknown angles.

From the condition it is known that the angle A is 50 °, the external angle at the vertex C is 130 °, and it is also known that AB = CB. In order to find unknown angles, let’s remember the properties of the outer corner of a triangle.

The outer angle of a triangle is equal to the sum of two angles of the triangle that are not adjacent to it.

That is, the outside angle C is equal to the sum of the inside angles A and B.

130 ° = 50 ° + B;

Angle B is 80 °.

And since the sides of the triangles are AB = CB, the triangle is equilateral and the angles at the base are equal to each other:

Angle A is equal to angle C and equal to 50 °