Question:
Mark $(\sqrt{)}$ against the correct answer in each of the following:
If $|\overrightarrow{\mathrm{a}}+\overrightarrow{\mathrm{b}}|=|\overrightarrow{\mathrm{a}}-\overrightarrow{\mathrm{b}}|$ then
A. $|\vec{a}|=|\vec{b}|$
B. $\vec{a} \| \vec{b}$
C. $\vec{a} \perp \vec{b}$
D. none of these
Solution:
