This is a trigonometry problem. We are given a right triangle with an unknown angle in which the opposite and adjacent sides of the angle are known (10 and 7). We also know that the tangent of any angle is the length of the opposite divided by the length of the adjacent. If we let the unknown angle be Ф, we can say that tan(Ф) = 10/7. To isolate Ф, all we have to do is take the inverse. In other words, Ф = arctan(10/7). Using a graphing calculator, we find that arctan(10/7) is approximately 55 degrees.
