A vector is inclined at equal angles to the three axes. If the magnitude of
is
find
Let l, m, n be the direction cosines of the vector r⃗
Vector r⃗ is inclined at equal angles to the three axes.
l = cosα, m = cos α, n = cosα
⇒ l = m = n.
Also, we know that -
l2 + m2 + n2 = 1
cos2α + cos2α + cos2α = 1
3 cos2α = 1
Hence, the direction cosines of the vector which are equally inclined to the axes are
∴ r⃗ = |r⃗ |( l î + m ĵ + n k̂)
(Given, |r⃗ | = 2√ 3 )
⇒ r⃗ = ±(2 î + 2ĵ + 2 k̂)