Angle Of Minimum Deviation (Prism & Spectrometer)

[leviathanX777]

Homework Statement

Hello, one of the things I have to do for my lab report for this week is to prove that the angle between the left and right deviations of the telescope is twice the angle of minimum deviation. Its a lab where you have to find the refractive index of substances using a prism and spectrometer.

Homework Equations

It also said to prove that when finding A, the angle of the prism, that the angle between the two telescope positions is twice the angle of the prism, A. I have already proven this using the theorem of angles at the centre and circumference of a circle easily.

The Attempt at a Solution

I'm not sure I was thinking that the proofs for these two theorems are the same but I'm not sure now as why would they be asking to prove this twice. Thanks

 

[kuruman]

It would be nice if you provided a picture showing the setup and the definitions of the angles that you are talking about. What two telescope positions? How is the minimum angle defined? Please put yourself in our position. Would you be able to figure out what it all means without a picture in your lab manual defining these quantities?