Question

The measure of the vertex angle in an isosceles triangle is six less than four time the measure of the base angle. find the measure of the vertex angle

Answer 1

An isosceles triangle is a special type of triangle that has two equal sides. Consequently, the two base angles are also equal. Since the interior angles of a triangle should sum up to 180°, the general equation should be

180° = 2*Base angle + Vertex angle

Let the base angle be x. Thus, the vertex angle is equal to
Vertex angle = 4x - 6
Substituting,
180 = 2x + 4x - 6
x = 31°

Vertex angle = 4(31°) - 6 
Vertex angle = 118°