If ` vec a\ a n d\ vec b` are vectors of equal magnitude, write the value of `( vec a+ vec b)dot( vec a- vec b)dot`

Explanation

Given: `|vec{a}|=|vec{b}|`……….(1)


`(vec{a}+vec{b}) cdot(vec{a}-vec{b}) `


`=|vec{a}|^{2}-|vec{b}|^{2} `


`=|vec{a}|^{2}-|vec{a}|^{2}` ……………. [use equation (1)]


`=0`