Question

Find the measure of the fourth angle of the quadrilateral if the three interior angles ${48}^o,{85}^o$ and ${140}^o$.

Answer 1

By angle sum property of a quadrilateral,

sum of all the interior angles$={360}^{\circ }$

Let $x$ be the fourth angle.

$\therefore {48}^{\circ }+{85}^{\circ }+{140}^{\circ }+x={360}^{\circ }$

$\therefore x={360}^{\circ }-{273‬}^{\circ }={87}^{\circ }$