Are Both Angles in Young's Double Slit Experiment Equal?

[member 392791]

I am trying to prove that the two θ are equal from this picture

http://en.wikipedia.org/wiki/File:Double_slit.svg

How do I go about proving this?

 

[DocZaius]

This might help: The small triangle's theta refers to the top angle of the triangle, not the left one. Also, the right angle is right. By that I mean that the angle on the right side of the triangle is a 90 degree angle. This post was an excuse to say that the right angle is right.

 

[member 392791]

Yes I was aware of which angles where which. I just used that picture since it was easily attainable. Any hints as to starting this

 

[jtbell]

Suppose you have two lines A and B that have angle θ between them.

If you have line C parallel to A, and line D parallel to B, then C and D also have angle θ between them, right?

Likewise, if you have line E perpendicular to A, and line F perpendicular to B, then E and F also have angle θ between them.

 

[sophiecentaur]

The phrase 'similar triangles' comes to mind and it hasn't yet been spelled out.