An object is at a very large distance from a concave mirror of focal length 40cm. Find the distance from the image to the mirror. Is the image real or virtual?
1/u + 1/v = 1/f
The Attempt at a Solution
1/u + 1/v = 1/40
The image has to be real because it must be outside the focus if it is very far from the mirror, right?
It seems to me like I haven't got enough information to solve the problem. How would I go about doing it? The answer from the key is 40cm.