00:01
In this problem, an ingoing or approaching ray makes a 35 degree angle with the normal of mirror a.
00:10
We will use the law of reflection to determine the angle of reflection from mirror b after reflecting off of mirror a.
00:18
First, we must note this equation, which is the law of reflection for normal mirrors, or planar mirrors.
00:31
This states that the incoming angle with respect to the normal is exactly equal.
00:35
To the reflected angle with respect to the normal of that mirror.
00:41
Using this equation on the first mirror tells us that the outgoing ray of light reflected off of mirror a will make another 35 degree angle with the normal.
00:55
Now we want to calculate the angle with respect to the normal of mirror b so that we can use this equation yet again.
01:07
In order to do this, recall that these mirrors are at a number 90 degree angle to each other.
01:13
Then we can look at this triangle here to calculate all of its interior angles and then find this angle theta i.
01:27
Okay, to do that, we must note that this angle forms a complementary angle with this 35 degree angle here...