Three Dimensional Geometry: JEE Main 2019 Mathematics question

The magnitude of the projection of the vector $\mathop {2i}\limits^ \wedge + \mathop {3j}\limits^ \wedge + \mathop k\limits^ \wedge$ on the vector perpendicular to the plane containing the vectors $\mathop {i}\limits^ \wedge + \mathop {j}\limits^ \wedge + \mathop k\limits^ \wedge$ and $\mathop {i}\limits^ \wedge + \mathop {2j}\limits^ \wedge + \mathop {3k}\limits^ \wedge$ , is :