Let the point (–1, α, β) lie on the line of the shortest distance between the lines x+2–3=y–24=z–52 and x+2–1=y+62=z–10. Then (α–β)2 is equal to _________. [2024]
(25)
Let L1 : x+2–3=y–24=z–52 and L2 : x+2–1=y+62=z–10
Let P(–3λ–2,4λ+2,2λ+5) be point on L1 and Q(–μ–2,2μ–6,1) be point on L2.
Direction ratios of PQ = (3λ–μ,2μ–4λ–8,–2λ–4)
Also, PQ→=|i^j^k^–342–120|=–4i^–2j^–2k^
i.e., 2i^+j^+k^
⇒ 3λ–μ2=2μ–4λ–81=–2λ–41
⇒ 3λ–μ=–4λ–8 and 2μ–4λ–8=–2λ–4
⇒ μ=7λ+8 and μ=λ+2
⇒ λ=–1 and μ=1
∴ Equation of PQ is, x+32=y+41=z–11
Now, (–1, α, β) lies on PQ
⇒ 1=α+4=β–1
⇒ α=–3, β=2
∴ (α–β)2=25.