Finding coordinates of reflected point in a plane

Question

So the question is:

Let $P$ be the point $(1,0,-2)$ and $\pi$ be the plane $x+y-2z+3=0$. Let $P'$ be the reflection of $P$ in the plane $\pi$. Find the coordinates of $P'$.

So far I know how to find the reflected point to a line by finding the foot of the perpendicular to the line (from the point). But I'm not even sure how to visualize a reflection in a plane. So would it be something like P' being on the opposite side of the plane from P? How would I solve this problem?

Answer 1

This picture might help you visualize since you already know the steps. Basically, the plane is a mirror and $P'$ is the virtual image of $P$.