What is the angle between two planes `2x-y+z=4 and x+y+2z=6`?

Options

A. `pi/2`
B. `pi/3`
C. `pi/4`
D. `pi/6`

Answer

B

Explanation

Given equations of two planes are `2x-y+z=4and x+y+2z=6`
So, angle between them is
`cos theta=(2(1)+(-1)(1)+(1)(2))/(sqrt(4+1+1)sqrt(4+1+1))`
`=(2-1+2)/(sqrt6sqrt6)=3/6=1/2`
`rArr theta=pi/3`