When presidents finish their term(s), they usually drift away behind the scenes. But this president has chosen to be a math teacher, renaming himself Barack ObaMATH. In his last days in the Oval Office,  he walks us through inverse trigonometric functions, in this stunning intro to the topic. We cover what inverse sin of ratios means, compared to just sin of angles. (Sometimes inverse sin is called arcsin.) We work with radians and degrees, in all four quadrants. The next video, part 2, works out further examples. Enjoy the Commander-in-TEACH, and YAY MATH!