Question

a side of the triangle below has been extended to form an exterior angle of 70°. 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.
Let the non - adjacent interior angles be $x$ and $50^{\circ}$, and the exterior angle be $70^{\circ}$. So, $x + 50^{\circ}=70^{\circ}$.

Step2: Solve for $x$

Subtract $50^{\circ}$ from both sides of the equation: $x=70^{\circ}- 50^{\circ}$.

Answer:

$20^{\circ}$