If `vecA= 2hati-2hatj-hatk and vecB= hati+hatj`, then :
(a) Find angle between `vecA and vecB`.
(b) Find the projection of resultant vector of `vecA and vecB` on x-axis.

Answer

(a) `90^(@)`
(b) 3

Explanation

(a) Let the angle between `vecA and vecB` is `theta`, then
`cos theta = (vecA*vecB)/(AB) = ((2hati- 2hatj-hatk))/(|2hati+ 2hatj -hatk||hati+hatj|)= (0)/(3sqrt2) =0`
`rArr theta = 90^(@)`
(b) Resultant vector
`(vecR)= vecA+ vecB= (2hati- 2hatj-hatk)+(hati+hatj)= 3hati-hatj-hatk`
`therefore ` projection of resultant of x-axis = 3.