When solving an angle for a right-angled triangle you need to use the acronym SOH CAH TOA, using the functions sin(x), cos(x) and tan(x). The other letters O, H and A represent the side of the triangle, standing for opposite, hypotenuse and adjacent. These are referring to the position of the side related to the angle you are trying to find. For example, the hypotenuse is the longest diagonal side, the opposite is the side furthest from the angle and the adjacent is the side touching the angle. Depending on what measurements you have (i.e., the lengths of two sides are given), you decide whether to use SOH, CAH or TOA. If the sides opposite and adjacent are provided, you would use TOA (as it includes only sides you know). From this, you put it into the equation tan(x) = opp / adj, then put the fraction into the calculator function 'tan^-1'. I would then do a worked example using a whiteboard.