Question

4b) Determine the measure of angle g.

Answer 1

g = 108°

Explanation:

You want angle (g) of the isosceles triangle with base exterior angle 144°.

Angle relations

Let b represent the measure of a base angle of the triangle.

b + 144° = 180° . . . the interior angle and exterior angle are supplementary

2b +g = 180° . . . . . the interior angles of a triangle total 180°

Solution

Using the first equation to substitute for b in the second equation, we have ...

2(180° -144°) +g = 180°

Subtracting the left-side constant gives ...

g = 2(144°) -180° = 288° -180°

g = 108°

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