Light is Reflecting-EASYYYY PROBLEM! but help needed.

The two acute angles in a right triangle sum to 90 degrees. They are complementary. Use that.

 

The angle between the incoming and the outgoing ray is the difference between the angle theta in your picture and the angle r' makes with the horizontal surface B (call it phi). Start labelling all of the angles you can find as either theta or 90-theta. You should be able to show phi=theta.

 

Thanks for the congrats. Yes, theta and phi are the angles the incoming and outgoing make with a horizontal line. If those are equal, they are parallel.

 

'teh diagram' that I'm looking at shows theta as the angle between the incoming ray and the normal to the vertical reflector - which is horizontal.

 

You are asked for the angle BETWEEN incoming and outgoing. If they are parallel, the angle between them is zero.

 

I think you just don't understand the question. You can't determine any of the angles in the problem. You aren't given any. All you can say is what the relation is between the angles. If you understand that the incoming and outgoing ray are parallel, then you are DONE. They make the same angle with the horizontal. The angle between them is ZERO. Write that answer down along with why you believe it and turn it in.