What is the angle between two planes having normal vectors as
→n1=ˆi+2ˆj+2ˆk and →n2=4ˆi−4ˆj+2ˆk ?
The correct option is B
We know that angle between two planes is equal to the angle between their normal vector.
cosθ=−−→n1 . −→n2(−→n1∣∣.(−→n2∣∣ =(ˆi+2ˆj+2ˆk) . (4ˆi−4ˆj+2ˆk)(√12+22+22) (√42+(−4)2+22 =0
So, the angle between the planes is 90∘.