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When I took algebra in high school, I learned about SOH-CAH-TOA. This is a mnemonic that helps you find missing information about a right triangle, if you know some of the information. For example the “SOH” in the mnemonic stands forine (of the angle) equals thepposite divided by thedjacent, where the opposite and adjacent are the lengths of two of the sides of the triangle. This is one of those things you learn in school where you say “okay I will learn it for the test, but I am never going to use this in my life.” Then at one point in my life I went to work for a surveyor’s office. Surveyors usually deal in horizontal distances. So if the deed or the survey says that going from point A to point B is 100 feet long, that means it is 100 feet horizontally. If it is steep, you may measure 120 feet on the ground from point A to point B, but when you remove the slope and just measure it as if it were flat, it is 100 feet. It was pointed out to me that we can easily measure the slope distance, and we can easily measure the angle of the slope. With these two pieces of information we can either calculate the elevation difference, or the horizontal distance using SOH-CAH-TOA. Suddenly that tiny piece of high school geometry came flooding back to me. Wow. It’s actually useful!