Find a vector of magnitude units which makes an angle of and with y and z - axes respectively.

Question

Philoid · Accepted Answer

Let l, m, n be the direction cosines of the vector r⃗

_{l = cosα,}

_{m = cosβ}

,

And, n = cosγ

= 0

Also, l² + m² + n² = 1

∴ r⃗ = |r⃗ |( l î + m ĵ + n k̂)

(Given, |r⃗ | = 3√ 2 )

⇒ r⃗ = ± 3 î + 3 ĵ