Let y = sin (ax) + cos (ax).
Use the symbolic manipulator of a computer algebra system (CAS) to help you with the following:
(a) Express y as a sinusoid for a = 2,3, 4, and 5.
(b) Conjecture another formula for y for a equal to any positive integer n.
(c) Check your conjecture with a CAS.
(d) Use the formula for the sine of the sum of two angles (see Exercise 56c) to confirm your conjecture.