List of top Mathematics Questions on Area Of A Parallelogram asked in JEE Main

Let \( \overrightarrow{OA} = \vec{a}, \overrightarrow{OB} = 12\vec{a} + 4\vec{b} \) and \( \overrightarrow{OC} = \vec{b} \), where \( O \) is the origin. If \( S \) is the parallelogram with adjacent sides \( OA \) and \( OC \), then\[\frac{\text{area of the quadrilateral OABC}}{\text{area of } S}\]is equal to ___.

Two adjacent sides of a parallelogram ABCD are given by  $\overrightarrow{AB}=2\hat{i}+10\hat{j}+11\hat{k} and \overrightarrow{AD}=-\hat{i}+2\hat{j}+2\hat{k}$.The side AD is rotated by an acute angel $\alpha$ in the plane of the parallelogram so that AD becomes AD'. If AD' makes a right angle with the side AB, then the cosine of the angle $\alpha$ is given by;