Question

The angle between `vecA = hati + hatj and vecB = hati - hatj` is
A. `45^(@)`
B. `90^(@)`
C. `-45^(@)`
D. `180^(@)`

Answer 1

Correct Answer - B
(b ) Given ,`A=hati +hatj`
and `B=hati-hatj`
We know that
A.B=|A||b|cos theta `
implies (hati+hatj).(hati-hatj)=(sqrt(1+1))(sqrt(1+1)) costheta`
where `theta` is the angle between A and B
`implies cos theta=(1-0+0-1)/(sqrt(2)sqrt(2))=(0)/(2)=0`
`implies theta90^(@)`