Mathematics Vectors & 3D Geometry questions from JEE Main 2025.
Consider the lines $\mathrm{L}_1: \mathrm{x}-1=\mathrm{y}-2=\mathrm{z}$ and $\mathrm{L}_2: \mathrm{x}-2=\mathrm{y}=\mathrm{z}-1$. Let the feet of the perpendiculars from the point $\mathrm{P}(5,1,-3)$ on the lines $\mathrm{L}_1$ and $\mathrm{L}_2$ be $Q$ and $R$ respectively. If the area of the triangle PQR is A , then $4 \mathrm{~A}^2$ is equal to :
Consider two vectors $\overrightarrow{\mathrm{u}}=3 \hat{\mathrm{i}}-\hat{\mathrm{j}}$ and $\overrightarrow{\mathrm{v}}=2 \hat{\mathrm{i}}+\hat{\mathrm{j}}-\lambda \hat{\mathrm{k}}, \lambda \gt 0$. The angle between them is given by $\cos ^{-1}\left(\frac{\sqrt{5}}{2 \sqrt{7}}\right)$. Let $\overrightarrow{\mathrm{v}}=\overrightarrow{\mathrm{v}}_1+\overrightarrow{\mathrm{v}}_2$, where $\overrightarrow{\mathrm{v}}_1$ is parallel to $\overrightarrow{\mathrm{u}}$ and $\overrightarrow{\mathrm{v}}_2$ is perpendicular to $\overrightarrow{\mathrm{u}}$. Then the value $\left|\overrightarrow{\mathrm{v}}_1\right|^2+\left|\overrightarrow{\mathrm{v}}_2\right|^2$ is equal to