Consider the function
Make a complete graph of the function.
Write a simpler trigonometric function that is represented by the same graph.
Which trig function passes through the origin?
Now use the angle sum identity to expand and simplify
Review the Math Notes box in this lesson and problem 12-108 for the Angle Sum Identities.
Does your work in part (c) agree with your graphical results from parts (a) and (b)? Explain.
Your answers should agree.