Trigonometry (?) help

I've been think for an hour about this and came to some basic conclusions, but I am unable to go any further;

There are two mirrors, each 1m in dimension, standing 1m apart. Between them is released a beam of light. What is the maximum angle one of the mirrors can deviate from being parallel to the other one, such that the beam will not escape the space between the mirrors for 0.001s.

So I have calculated how the angles at which the beam will be reflected are related to the angle of deviation, and some initial lengths, but I don't know what to do with this one later. Help please?

The light will bounce back and forth a number of times. What you need to do is use the speed of light and the distance between the mirrors to figure out how many bounces you'll get. Then apply trig to get the maximum angle.