Question

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

Explanation:

Step1: Apply the exterior angle theorem

The exterior angle theorem states that an exterior angle of a triangle is equal to the sum of the two non - adjacent interior angles. So, \(129^{\circ}=x^{\circ}+114^{\circ}\).

Step2: Solve for \(x\)

Subtract \(114^{\circ}\) from both sides of the equation: \(x = 129 - 114\).

Answer:

\(x = 15\)