An angle whose measure is $90^{\circ}$ is called a $\ldots \ldots \ldots$

In $\Delta PQR$,$\angle P : \angle Q : \angle R = 5 : 2 : 2$. Find the measure of each angle of $\Delta PQR$.

The sum of the three angles of a triangle is $\ldots \ldots \ldots$ (in $^o$)

In the following figure,lines $AB$ and $CD$ intersect at $O.$ If $\angle AOC + \angle BOE = 100^{\circ}$ and $\angle BOD = 40^{\circ},$ find $\angle BOE$ and reflex $\angle COE.$

Two adjacent angles are equal. Is it necessary that each of these angles will be a right angle? Justify your answer.

$\angle PQR$ and $\angle PQS$ are a linear pair of angles. If $11 \angle PQR = 9 \angle PQS$,then find $\angle PQR$ and $\angle PQS$.