JEE Advanced2009MathematicsThree Dimensional GeometryActual
A line with positive direction cosines passes through the point P(2,-1,2) and makes equal angles with the coordinate axes. The line meets the plane 2 x+y+z=9 at point Q . The length of the line segment P Q equals
Options
- A1
- B2
- C3
- D2
Correct answer
C. 3
Step-by-step solution
Since, l=m=n= 1 3 Equation of line are gathered x-2 1 / 3 = y+1 1 / 3 = z-2 1 / 3 x-2=y+1=z-2=r (say) gathered Any point on the line is Q (r+2 r-1, r+2) Q lies on the plane 2 x+y+z=9 aligned & 2(r+2)+(r-1)+(r+2)=9 & 4 r+5=9 r=1 Q(3,0,3) & P Q= (3-2)^2+(0+1)^2+(3-2)^2 & = 3 aligned