19-18-17/16-15-14-13-12-11-10-8-7 The curve above is the graph of a sinusoidal function. It goes through the points (-9,0) and (5, 0). Find a sinusoidal function that matches the given graph. If needed, you can enter -3.1416... as 'pi' in your answer, otherwise use at least 3 decimal digits.