Question
If $$Q$$ is the image of the point $$P\left( {2,\,3,\,4} \right)$$ under the reflection in the plane $$x - 2y + 5z = 6,$$ then the equation of the line $$PQ$$ is :
A.
$$\frac{{x - 2}}{{ - 1}} = \frac{{y - 3}}{2} = \frac{{z - 4}}{5}$$
B.
$$\frac{{x - 2}}{1} = \frac{{y - 3}}{{ - 2}} = \frac{{z - 4}}{5}$$
C.
$$\frac{{x - 2}}{{ - 1}} = \frac{{y - 3}}{{ - 2}} = \frac{{z - 4}}{5}$$
D.
$$\frac{{x - 2}}{1} = \frac{{y - 3}}{2} = \frac{{z - 4}}{5}$$
Answer :
$$\frac{{x - 2}}{1} = \frac{{y - 3}}{{ - 2}} = \frac{{z - 4}}{5}$$
Solution :
Let $$Q$$ be the image of the point $$P\left( {2,\,3,\,4} \right)$$ in the plane $$x - 2y + 5z = 6,$$ then $$PQ$$ is normal to the
plane.
$$\therefore $$ direction ratios of $$PQ$$ are $$\left\langle {1,\, - 2,\,5} \right\rangle $$
Since $$PQ$$ passes through $$P\left( {2,\,3,\,4} \right)$$ and has direction ratios $${1,\, - 2,\,5}$$
$$\therefore $$ Equation of $$PQ$$ is $$\frac{{x - 2}}{1} = \frac{{y - 3}}{{ - 2}} = \frac{{z - 4}}{5}$$