Question

Prove that sum of all angles of triangle is ${180}^0$.

Answer 1

Draw a line passing through A, such that it is parallel to BC.

$⟹\angle ABC=\angle BAP$ (alternate angles)

and$\angle ACB=\angle CAQ$ (alternate angles)

$⟹\angle BAP=y$

$\angle CAQ=z$

$\because$ Sum of angles on a straight line$={180}^{\circ }$

Hence, proved.