The graph of a cosine function shows a reflection over the x-axis, an amplitude of 2, a period of 4, and a phase shift of 0.5 to the right. Which is the equation of the function described? of (x) = -2 cos (xx - -.) of ( x ) = -2cost - 4 of ( x) = -2cos (nx - 5 of ( x) = -2cos 2The sinusoidal function f (x) = 42 sin (9x - 7 ) + 42 models the height, in centimeters, that a valve stem of the a tire IS above ground x seconds after the tire begins to rotate.' How long does it take the valve stem to complete one revolution? Enter your answer, rounded to the nearest hundredth of a second, in the box