Physics and Astronomy Labs/Distance and angular size
Measured the width of hall to be 9 feet. The angular size was three fingers. (Perhaps 4 degrees?). Using 57 degrees for 1 radian, and adding the 9 ft hall width to our answer, we obtain:
![](http://upload.wikimedia.org/wikipedia/commons/thumb/0/04/Angular_size_hallway.png/400px-Angular_size_hallway.png)
57*9/4 + 9 =137 feet.
Compare this wih 30.36 meters using parallax.