Question

A laser source is in the point ( 4 , 0, 2 ) and is directed towards a plane mirror with equation: 2x -y- z = 0 .
The beam reflected from the mirror in a point P and then hits a target with coordinates (3, 2 , -2 ).
Determine coordinates of the point P.

Answer 1

use this: angle of incidence = angle of reflection

Answer 2

angle of incidence/reflection:

the angle which an incident/reflected ray makes with a perpendicular to the surface at the point of incidence.

Answer 3

hmm, that gives us two equations and 3 variables

Answer 4

we should also use: normal, incident ray, reflected ray should all lie on the same plane

Answer 5

you will need the "cross product" to find the plane in which the two rays and the normal lie. (perhaps you have learnt cross product by some other name?)