Question

If an exterior angle of a triangle is ${130}^0$ and one of the interior opposite angle if ${60}^0$ . Find the other interior opposite angle.

Answer 1

We have the property of exterior and interior angles,

Exterior angle is equal to the sum of interior opposite angles.

From triangle $ABC$ is figure above,

$\angle ACD=\angle ABC+\angle BAC$

Let, $\angle ABC={60}^{\circ }$

$\angle ACD={130}^{\circ }$

$\therefore {130}^{\circ }={60}^{\circ }+\angle BAC$

$\angle BAC={130}^{\circ }-{60}^{\circ }={70}^{\circ }$ This is the value of the other opposite angle.