Question

In a parallelogram $ABCD,$ the bisectors $\angle A$ and $\angle B$ and at $0.$ Find $\angle AOB.$

Answer 1

$\angle A+\angle B={180}^o$

$2x+2y={180}^o$

$x+y={90}^o$

$△AOB\Rightarrow x+y+\angle AOB={180}^o$

${90}^o+\angle AOB={180}^o$

$\angle AOB={90}^o$