What's my latitude?

Today at noon local solar time, I noticed that an east-west line of the sun on the floor under a skylight was 4 feet to the north of the edge that made the line. The edge that made the line was 9 feet off the floor. How many degrees would I need to travel south to get the sun to be directly overhead today? What's my latitude?

No takers? On June 21, the sun is about 23 degrees north of the equator. So, if my latitude were 23 degrees north, the sun would be directly overhead at local noon. But the shadow is slanted at an angle whose tangent is 4/9. Now whip out your handy-dandy scientific calculator, and find the arc tangent of 0.444. Arc tangent may show up labeled as "tan-1". You say you don't have a calculator with arctan? Open Excel or any other spreadsheet and enter the following formula in a cell

=180/PI()*ATAN(4/9)

The arctan function (ATAN) delivers its result in radians, which is why you need to multiply by 180/pi.

Okay, now can you tell me my latitude?