Question

The angle between the vectors A = i + j and B= i- j is * 1 point (a) 45˚ (b) 90˚ (c) -45˚ (d) 180˚

Answer 1

Answer:

we know costheta=A^.B^/A.B

A=i^+j^ and B=i^-j^

A^.B^=i^+j^(i^-j^)=0

A.B=square root of (1)2+(1)2 .square root of (1)2+(_1)2=2root of 2

then

cos theta=0/2root2=0

cos theta = cos 90 that is theta = 90 degree