Question

If `A = <3 ,-1 ,3 >`, `B = <2 ,-3 ,5 >` and `C=A-B`, what is the angle between A and C?

Answer 1

`112.47^0`

Explanation:

C= A-B= <3,-1,3>- <2, -3, 5> = < 1,2,-2>

Angle between A and C would be given by `cos theta=(A*C)/(|A| |C|)`

`cos theta = (3*1 +(-1)*2 + 3(-2))/ (sqrt(3^2 +(-1)^2 +3^2) sqrt(1^2+2^2 +(-2)^2))`

=`-5/(sqrt19 sqrt9)`= -0.3823

`theta= arccos-0.3823` =`112.47^0`