Wei is standing in wavy water and notices the depth of the waves varies in a periodic way that can be

modeled by a trigonometric function. he starts a stopwatch to time the waves.

after 1.1 seconds, and then again every 3 seconds, the water just touches his knees. between peaks, the

water recedes to his ankles. wei's ankles are 12 cm off the ocean floor, and his knees are 55 cm off the

ocean floor.

find the formula of the trigonometric function that models the depth d of the water t seconds after wei

starts the stopwatch. define the function using radians.