If a vector having magnitude of 5 units, makes equal angle with each of the three mutually perpendicular axes, then the sum of the magnitude of the projections on each of the axis is
🎥 Video solution / Text Solution of this question is given below:
Vector Projection Problem
Given: A vector of magnitude 5 makes equal angles with x, y, and z axes. To Find: Sum of magnitudes of projections on each axis.
Let angle with each axis be \( \alpha \). Then, from direction cosine identity:
\[
\cos^2\alpha + \cos^2\alpha + \cos^2\alpha = 1 \Rightarrow 3\cos^2\alpha = 1
\Rightarrow \cos\alpha = \frac{1}{\sqrt{3}}
\]
Projection on each axis: \( 5 \cdot \frac{1}{\sqrt{3}} \)
Sum = \( 3 \cdot \frac{5}{\sqrt{3}} = \frac{15}{\sqrt{3}} = \boxed{5\sqrt{3}} \)