# Homework Help: Kinematic Distance Problem? Can't Tell

1. Jan 28, 2010

1. The problem statement, all variables and given/known data
An observer on the earth observes the angle subtended by the diameter of the moon to be 0.009199 radians. If the moon is 234,800 miles away, what is its diameter?

2. Relevant equations

3. The attempt at a solution
Not quite sure where to begin with this one. I think it may be a kinematics distance problem but not 100% sure. Suggestions?

2. Jan 28, 2010

### Lok

This is a common trigonometry problem.

Go from there.

3. Jan 28, 2010

### Lok

Btw the result must be somewhere around 4 times less than the earths so around 3100 km or 1500 miles.

4. Jan 28, 2010

still not sure where to begin as far as equations go.

how do we know it will be 4 times less than the earth?

5. Jan 28, 2010

### Lok

This is general knoledge.

Imagine a triangle with one point the observer, and the other the poles of the moon, you have one angle and a distance which is the height of the trianlge in the Observers point....