Determine whether the following pair of lines intersect or not :
and
z = 2
Given: - Two lines equation: and
; z = 3
We have,
⇒ x = 2λ + 1, y = 3λ – 1 and z = λ
So, the coordinates of a general point on this line are
(2λ + 1, 3λ – 1, λ)
The equation of the 2nd line is
⇒ x = 5μ + 1, y = μ + 2 and z = 3
So, the coordinates of a general point on this line are
(5μ + 1, μ + 2, 3)
If the lines intersect, then they must have a common point.
Therefore for some value of λ and μ, we have
⇒ 2λ + 1 = 5μ + 1 , 3λ – 1 = μ + 2, and λ = 3
⇒ 2λ – 5μ = 0 ……(i)
⇒ 3λ – μ = 3 ……(ii)
and λ = 3 ……(iii)
putting the value of λ from eq iii in eq ii, we get
⇒ 3λ – μ = 3
⇒ 3(3) – μ = 3
⇒ μ = 6
As we can see by putting the value of λ and μ in eq i, that it does not satisfy the equation.
Check
⇒ 2λ – 5μ = 0
⇒ 2(3) – 5(6) = 0
⇒ – 24 = 0
⇒ LHS≠RHS; Hence intersection point exists or line does not intersects.