# Ratio of Sun's diameter to Moon's

1. Jul 2, 2010

### rtsphysics

1. The problem statement, all variables and given/known data
During a total solar eclipse, your view of the Sun is almost exactly replaced by your view of the moon. Assuming that the distance from you to the sun is 400 times the distance from you to the moon, find the ratio of the Sun's diameter to the moon's diameter.

2. Relevant equations

3. The attempt at a solution
I started by drawing three circles: the Sun at the left of the moon at the left of the Earth. After this, I'm stuck. The problem never states whether the given distances from "you to the moon/sun" include the radius of the moon or sun. Even if it does, I have no idea how to proceed. I read the post about this exact problem (https://www.physicsforums.com/showthread.php?t=318386), but I didn't get how to use similar triangles.

2. Jul 2, 2010

### mgb_phys

Try drawing two similar triangles, one with the moon's diamter as the base and one with the sun's - you know the length of the sides of the moon triangle