Reflecting telescope optics problem-Angle on the sky to angle on a mirror

[Desafino]

Homework Statement

When viewed from Earth, the Moon subtends an angle of 0.5° in the sky. How large an image of the Moon will be formed by the 3.6 m diameter mirror of the Canada-France-Hawaii Telescope, which has a focal length of 8.5 m?

Homework Equations

1/s + 1/s' = 1/f, but I'm not sure what else.

The Attempt at a Solution

I'm really not sure where to begin. My book only talks about refracting telescopes and we've yet to talk about reflecting telescopes in class. I thought initially it might have something to do with the distance to and radius of the moon but I couldn't figure out how to work those into the problems. I'd appreciate any help you have. Thanks!

 

[Basic_Physics]

The angle the object subtended at the mirror is the same angle that the image subtends - just like for refracting telescopes.