The component of a vector $A$ at an angle $\theta$ to itself is,
\[A_x=A\cos\theta\]
At right angle, \[A_x=A\cos90°=0\]
Hence, the magnitude of component of a vector right angle to itself is zero.
The component of a vector $A$ at an angle $\theta$ to itself is,
\[A_x=A\cos\theta\]
At right angle, \[A_x=A\cos90°=0\]
Hence, the magnitude of component of a vector right angle to itself is zero.