(adsbygoogle = window.adsbygoogle || []).push({});

I can't see how the textbook produces the following relationships between angles:

$$ \theta = \phi + \alpha \qquad (1)$$

$$ 2\theta = \alpha + \alpha ' \qquad (2)$$

My thinking is that the exterior angle theorem for triangles was used to create expression ##(1)##, but I am unsure as to how expression ##(2)## came about. Was the exterior angle theorem simply used twice to produce both equations?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# I Geometrical Optics - Light ray angles on a spherical mirror

Tags:

Have something to add?

**Physics Forums | Science Articles, Homework Help, Discussion**