Question

find the measure of the third exterior angle in this triangle. 120° 125° ?

Explanation:

Step1: Recall the exterior angle sum formula

The sum of exterior angles of any polygon (including a triangle) is \(360^{\circ}\). Let the three exterior angles be \(x = 120^{\circ}\), \(y=125^{\circ}\), and \(z\) (the unknown). The formula is \(x + y+z=360^{\circ}\).

Step2: Solve for \(z\)

Substitute \(x = 120^{\circ}\) and \(y = 125^{\circ}\) into the formula \(z=360^{\circ}-(x + y)\). So \(z=360^{\circ}-(120^{\circ}+ 125^{\circ})\). First calculate \(120^{\circ}+125^{\circ}=245^{\circ}\). Then \(z = 360^{\circ}-245^{\circ}=115^{\circ}\).

Answer:

\(115^{\circ}\)