Question

question a side of the triangle below has been extended to form an exterior angle of 129°. find the value of x.

Explanation:

Step1: Recall exterior - angle property

The exterior angle of a triangle is equal to the sum of the two non - adjacent interior angles. So, $129^{\circ}=x + 112^{\circ}$.

Step2: Solve for $x$

Subtract $112^{\circ}$ from both sides of the equation: $x=129^{\circ}-112^{\circ}$.

Answer:

$x = 17^{\circ}$