how does an optical golf range finder (no laser, no sonics) work?

Question

could it be used to measure other distances? how (as, with the golf one, it tells you to gauge by the bottom and top of the flagpole, objects not always conveniently about the place)? how may its accuracy be determined? be gentle with the math, por favor; algebraic notations, and above, burn me like holy wa... i mean, uh, acid. definitely acid (i know it's a trig problem, so i'm wary).

Answer 1

You measure the angle between the top and the bottom of the flag. sin(angle)= height of flag/distance
distance=height of flag/sin(angle)

Depending on how you draw your triangle, you may get tan instead of sin, but for small angles sin and tan gives the same result