Question

The line of the angle between two vectors a = 3i+j+k, b= 2i-2j+k

Answer 1

a=√9+1+1=√11
b=√4+4+1=√9=3
now as we know a.b=ab cos theta

so a.b=6-2+1=5

5=√11×3cos theta
cos theta=5/√11×3
theta =cosinverse 5/√11×3


hope it helps..