Question

IF A BASE ANGLE OF AN ISOSCELES TRIANGLE MEASURES 50,WHAT IS THE NUMBER OF DEGREES IN THE MEASURE OF THE VERTEX ANGLE?

Answer 1

If a base angle of an isosceles triangle measures 50, what is the number of degrees in the measure of the vertex angle?

Solution:

We know that $\angle A = 50{}^{\circ}$ . Because $\Delta ABC$ is the isosceles triangle then

$$\angle A = \angle B = 5 0 {}^ {\circ}.$$

The sum of the interior angles of a triangle is $180{}^{\circ}$ . So

$$\angle A + \angle B + \angle C = 1 8 0 {}^ {\circ},$$ $$5 0 {}^ {\circ} + 5 0 {}^ {\circ} + \angle C = 1 8 0 {}^ {\circ},$$ $$\angle C = 8 0 {}^ {\circ}.$$

Answer:

80 (degrees)