Question

What are the angles which the vector A=3i+6j makes with the cordinate axis

Answer 1

Find the angles which the vecotr v ⃗ =3i−6j+2k v→=3i−6j+2k makes with the coordinate axes.
If the angles are α,β,θ α,β,θ , show that for any 3-dimensional vector:
. . . cos 2 α+cos 2 β+cos 2 θ=1 cos2⁡α+cos2β+cos2⁡θ=1