In triangle ABC, angle A = 45 ° and angle B = 110 °. Find the outside angle at vertex C.

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.

In order to find the external angle at the vertex ∠С, you need to find the degree measure of the internal angle ∠С.

The sum of all the angles of the triangle is 180º. Based on this:

∠С = 180º – ∠А – ∠В;

∠С = 180º – 45º – 110º = 25º.

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

φ = 180º – ∠С;

φ = 180º – 25º = 155º.

Answer: the degree measure of the external angle at the vertex С is equal to 155º.