Question

Two lines L₁: (x – x₁)/a₁ = (y – y₁)/b₁ = (z – z₁)/c₁

and L₂: (x – x₂)/a₂ = (y – y₂)/b₂ = (z – z₂)/c₂ are coplanar if

|((x₂ - x₁,y₂ - y₁,z₂ - z₁),(a₁,b₁,c₁),(a₂,b₂,c₂))| = 0

If the lines (x – 1)/2 = (y + 1)/3 = (z – 1)/4 and (x – 3)/1 = (y – k)/2 = z/1 are coplanar, the value of k is

(a) 3/2

(b) 9/2

(c) –2/9 

(d) –3/2

Answer 1

Answer is (b) 9/2

Since both the lines are coplanar, so