If the length of the perpendicular drawn from the point (a,4,2), a>0 on the line x+12=y-33=z-1-1 is 26 units and Q(α1,α2,α3) is the image of the point P on this line, then a+∑i=13αi is equal to
(8)
Given line X+12=Y-33=Z-1-1=λ
X=2λ-1, Y=3λ+3, Z=-λ+1
(2λ-1-a)2+(3λ-1)3+(-λ-1)(-1)=0
⇒4λ-2-2a+9λ-3+λ+1=0
14λ-4-2a=0⇒7λ-2-a=0
⇒(5λ-1)2+(3λ-1)2+(λ-1)2=24
35λ2-14λ-21=0⇒(λ-1)(35λ+21)=0
For, λ=1⇒a=5
Let (α1,α2,α3) be reflection point P
α1+5, α2+4=12, α3+2=0
α1=-3, α2=8, α3=-2
α1+α2+α3=8