# Finding image location with concave mirror

## Homework Statement

A small object is located 32.0cm in front of a concave mirror with a radius of curvature of 40.9cm.
Where will the image be formed?

tan(θ)=-h/di
f=1/2R?

## The Attempt at a Solution

Haven't been able to solve for theta. I'm not sure what equation to use, but I'm guessing that the radius is important. Do I need to find the focal length?

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Redbelly98
Staff Emeritus
Homework Helper
Welcome to Physics Forums.

Yes, you need to find the focal length first. And, your text book should have a formula that relates focal length to the positions of the object and image, that will be helpful here.

you do need to know the focal length. You have to be careful with equations. focal length =R/2 not....1/2R....do you see what I mean/

Ohhhh, I see. I use 1/do + 1/di = 2/R (which is the focal point, & the reason the difference is indicated). Thank you both!

Redbelly98
Staff Emeritus