What is the frequency of the sinusoidal graph?

A sinusoidal function with the x axis beginning at negative pi over 2 and increasing in increments of pi over two until reaching five pi over two. The function begins at zero comma one and then decreases to a minimum value of pi over two comma negative one, increases to a maximum value of pi comma one and then decreases back to a minimum value of three pi over two comma negative one. The function then increases to a maximum value of two pi comma one and then decreases to a minimum value of five pi over two comma negative one.