Does the conical angle of a shock wave open wider, narrow

Solution 44E As the speed of the supersonic aircraft increases, the Mach number also increases (M = v/a , v = speed of aircraft, a = speed of air). This increase in Mach number is related to the decrease in the conical angle (M = 1/sin , is the half of the conical angle). Therefore, the angle narrows down with the increase in the aircraft speed.