(a) Rewrite the given integral in a form that does not involve a power of cosine. Choose the correct answer below.
(b) Use a change of variables to evaluate the second of these integrals. What is the best choice of u for the change of? variables?
(c) Find du.
(d) Rewrite the second of the two integrals found above using this change of variables.
(d) Evaluate the definite integral.