The sum of the outer angles at the base of an isosceles triangle = 260 degrees. find the interior corners

A triangle is three points that do not lie on one straight line, connected by segments. In this case, the points are called the vertices of the triangle, and the segments are called its sides.

Since the angles at the base are equal in an isosceles triangle, the outer angles at the vertices ∠A and ∠C will also be equal. In this way:

φ = 260º / 2 = 130º.

Since the sum of the outer and inner angles of the triangle is 180º, then:

∠А = ∠С = 180º – 130º = 50º.

Since the sum of all the angles of the triangle is 180º, then:

∠В = 180º – ∠А – ∠С;

∠В = 180º – 50º – 50º = 80º.

Answer: ∠А = 50º, ∠С = 50º, ∠В = 80º.