Question

Find the angle between the lines whose direction cosines are given by the equation 6mn – 2nl + 5lm = 0, 3l + m + 5n = 0

Answer 1

Given 6mn – 2nl + 5lm = 0 

3l + m +5n = 0. 

From (2), m = 3l – 5n

Putting the value of m in equation (1), we get,

(a₁, b₁, c₁) = (-2, 1, 1) and (a₂, b₃, c₃) = (1, 2, -1)