Lola is riding her bicycle when a piece of gum gets stuck to the wheel. A graph of the situation is shown at right.

1. What is the diameter of Lola’s bicycle wheel?

   Hint (a):

   The diameter is double the amplitude of the graph.

2. How fast is Lola’s bicycle wheel spinning (in revolutions per second)?

   Hint (b):

   How long does it take to complete one full cycle of the graph?

3. Write an equation to model this situation.

   Hint 1(c):

   The parent graph is $y = a \text{cos}\left(bx\right)$

   Hint 2(c):

   There is a vertical shift.

   The graph is flipped over.