Question

The isosceles trapezoid is part of an isosceles triangle with a 42 degree vertex

Answer 1

Answer:

the measure of the obtuse base angle of the trepezoid is 111.

Step-by-step explanation:

An isosceles triangle has one vertex angle and two congruent base angles. Also, we know that the sum of all angles in a triangle must equal 180 degrees. So we can say that:

Vertex Angle + Base Angle + Base Angle = 180.

Vertex Angle + 2 x (Base Angle) = 180.

2 x (Base Angle) = 180 - Vertex Angle

2 x (Base Angle) = 180 - 42

2 x (Base Angle) = 138

Base Angle = 69

Also, we know that angles on one side of a straight line always add to 180 degrees.

So we can say that:

Base Angle + ? = 180

? = 180 - Base Angle

? = 180 - 69

? = 111

So, the measure of the obtuse base angle of the trepezoid is 111.