Question

The angle of a quadrilateral are respectively ${100}^o,{98}^o,{92}^o$. Find the fourth angle.

Answer 1

Let the fourth angle be $x^o$.

Then, by angle sum property of quadrilateral,

${100}^o+{98}^o+{92}^o+x^o={360}^o$

$x^o={360}^o-{290}^o={70}^o$

Hence, the measure of fourth angle is ${70}^o$.