As a wave passes by the height of the water is modeled by ht

As a wave passes by, the height of the water is modeled by h(t)=9cos(5/9t), where h(t) is the height in feet above mean sea level. Find the height of the wave. (That is, find the vertical distance between the trough and the crest of the wave.)

a) 9

b)10/9

c) 18

d) -9

e) 5/9

Solution

h(t)= 9cos(5/9t)

Max Amplitude = 9

Miniumu Ampltiude = -9

So, distance between max. and min. = distance between the trough and the crest of the wave

= 9 - (-9) = 18

Option c