How far is the image of the star from the concave mirror?

[leehom]

Homework Statement

The light from a star reflects from a concave mirror with a radius of curvature of 1.70 m. Determine how far the image of the star is from the surface of the mirror.

Speed of light = 3.0 x 10^8 m/s
r = 1.7 m
f = 0.85 m

1/di + 1/do = 1/f... and then I'm stuck b/c i don't know what di or do are

 

[Kurdt]

A stars light is considered as coming from infinity.

 

[leehom]

Okay... but that doesn't help me solve di or do...

 

[Kurdt]

Well the star is the object isn't it. So the object distance is infinity.