I’ve received a couple of trig questions lately. I liked trig in high school and college, but I can’t say I put it to use much. There’s only one thing that you need to know about Excel and trigonometric functions: Everything is in radians, not degrees. If you do anything trig-related in Excel, you have to convert to degrees (unless you want radians, of course).
Here’s one problem:
In this example, Peter knows a fixed point on a plot of land. He also knows the coordinates were the corner of a building will be when it’s built. He wants to figure the angle and distance from the known point to the corner of the building so he can point his theodolite at it.
I had to look up theodolite, and it turns out I’ve been calling it a transit all these years.
Finding the distance is easy, thanks to old Pythagoras and his right triangle formula, c2 = a2 + b2. The formula in B4 is: =SQRT((B1^2)+(B2^2)). That one I didn’t have to look up. The rest of of the trig functions weren’t so quick to return to me.
Next I needed the angle. Cell B5 is =DEGREES(ATAN(B2/B1)). Note that I didn’t forget to convert to degrees, since the ATAN function would return radians. To refresh my memory, I used this Trigonometric Formula page.
Finally, I turned that fractional angle into minutes and seconds, thusly:
Now Peter can point his theodolite (or whatever you do with those things) at 75° 57′ 1″ and 6,185mm away will be the start of the new building.