Question 12 Marks
In a parallelogram ABCD, if $\angle\text{D} = 115^\circ,$ then write the measure of $\angle\text{A.}$
Answer
View full question & answer→In Parallelogram $ABCD , \angle A$ and $\angle D$ are Adjacent angles. We know that in a parallelogram, adjacent angles are supplementary. Now, $\angle A +\angle D =180^{\circ} \Rightarrow \angle A +115^{\circ}=180^{\circ} \Rightarrow \angle A =180^{\circ}-115^{\circ} \Rightarrow \angle A =65^{\circ}$ So, measure of $\angle A$ is $65^{\circ}$.
$\angle\text{ABC}=90^\circ$ $\Rightarrow\angle\text{ABD}+\angle\text{DBC}=90^\circ$ $\Rightarrow40^\circ+\angle\text{DBC}=90^\circ$ $\Rightarrow\angle\text{DBC}=50^\circ$


