Question

Antonio's toy boat is bobbing in the water next to a dock. Antonio starts his stopwatch, and measures the vertical distance from the dock to the height of the boat's mast, which varies in a periodic way that can be modeled approximately by a trigonometric function. The vertical distance from the dock to the boat's mast reaches its highest value of -27 \text{ cm}−27 cmminus, 27, space, c, m every 333 seconds. The first time it reaches its highest point is after 1.31.31, point, 3 seconds. Its lowest value is -44\text{ cm}−44 cmminus, 44, space, c, m. Find the formula of the trigonometric function that models the vertical height HHH between the dock and the boat's mast ttt seconds after Antonio starts his stopwatch. Define the function using radians.

Answer 1

Explanation:

Since we're given a time at which the height is maximum, we can use a cosine function for the model.

The amplitude is half the difference between the maximum and minimum: (-27 -(-44))/2 = 8.5 cm.

The mean value of the height is the average of the maximum and minimum: (-27 -44)/2 = -35.5 cm.

The period is given as 3 seconds, and the right shift is given as 1.31 seconds.

This gives us enough information to write the function as ...

H(t) = (amplitude)×cos(2π(t -right shift)/period) + (mean height)

H(t) = 8.5cos(2π(t -1.31)/3) -35.5 . . . . cm