A 5cm mirror is just large enough to show the whole image ...

Thread Starter

famous

Joined Nov 24, 2012
3
A 5cm mirror is just large enough to show the whole image of a tree when held 20 cm from the eye of the observer whose distance to the tree is 100 m. What is the height of tree?
 

MvGulik

Joined Nov 3, 2011
41
Mmm. Lets see.

Find total light traveling distance.
Divide that by the eye to mirror distance.
Multiply that by height of the mirror.
That should return the height of the tree.
 
Last edited:

Markd77

Joined Sep 7, 2009
2,806
Try drawing it, essentially I think it is the same as looking through a 5cm hole, you should be able to calculate the ratios of the triangle sides and the height of the tree. (The distance from the eye to the tree should really include the distance to the mirror, and it actually makes a difference which direction you are holding the mirror relative to the tree, but the question is probably ignoring that).
 
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