mathproblemgenerator.com provides a video about how to find a central angle with a given radius and a tangent. The angle at the intersection of the radius and the tangent is equal to 90 degrees. The second angle is also given in the problem. So the central angle is equal to 180 minus (90 plus the other angle given). In the video, the given angle is 54 degrees, making the equation = 180 - (90 + 54). Therefore the central angle is equal to 36.
The video is a simple and quick way to learn this computation for the central angle. It provides visuals so that the diagram and the solutions are seen step by step.