BITSAT2012MathematicsThree Dimensional GeometryActual
Find the coordinates of the point where the line joining the points (2,-3,1) and (3,-4,-5) cuts the plane 2 x+y+z=7
Options
- A(1,2,-7)
- B(1,-2,7)
- C(-1,-2,7)
- D(1,2,7)
Correct answer
B. (1,-2,7)
Step-by-step solution
The direction ratios of the line are 3-2,-4-(-3),-5-1 i.e. 1,-1,-6 Hence equation of the line joining the given points is x-2 1 = y+3 -1 = z-1 -6 =r( say ) Coordinates of any point on this line are (r+2,-r-3,-6 r+1) If this point lies on the given plane 2 x+y+z=7 then 2(r+2)+(-r-3)+(-6 r+1)=7 r=-1 Coordinates of any point on this line are (-1+2,-(-1)-3,-6(-1)+1) i.e. (1,-2,7)