Each labeled point on the graph at right is either a maximum or a minimum.

1. Find the period and amplitude of the graph.

   Hint (a):

   Period: How far is it between consecutive maximums or minimums?
   Amplitude: How “tall” is the graph? Divide this answer by $2$.

2. Find an equation for the graph.

   Hint (b):

   Find the vertical and horizontal shifts. For the vertical shift, what number is in the middle of $23$ and $−17$?

   More Help (b):

   Review the Math Notes box in Lesson 7.2.4 for help with the general equation of a sine or cosine graph.
   In this case, it is more convenient to use cosine because you know a maximum point.

   Possible Answer (b):

   $y=3+20\cos\left( \frac{\pi}{22}(x-15) \right)$

3. Use one of the labeled points to check your equation.

   Hint (c):

   Substitute the values for each of the points into the equation to verify that it is correct.