15. (4 pts.) A weight is attached to the end of a frictionless spring, pulled down to extend the spring, and then released. Let d be the distance of the weight above
the floor at time I, where d is in centimeters and is in seconds. The distance
varies sinusoidally over time. A stopwatch reads 0.0 seconds when the weight is at
it's low point of Il centimeters above the floor. It's first high point 42 centimeters
above the floor occurs at 1.2 seconds. Write a trigonometric equation to express
d in terms of t.