When will the magnitude of the resultant of two equal vectors be
(i) `sqrt(2)` times and

Explanation

Let the value fo each vector be a and the angle between the two vectors be `alpha`.
(i)In this case, the magnitude of the resultant =`sqrt(2a)`
`therefore (sqrt(2a))^2=a^2+a^2+2a*a cos alpha`
or, `2a^(2) cos alpha =0 or, cos alpha =0 = cos 90^(@)`
`therefore alpha=90^(@)`
Hence , the angle between the two vectors will be `90^(@)`.