Consider the function f (x) = sin4 x + cos4 x
(a) Use the power-reducing formulas to write the function in terms of cosine to the first power.
(b) Determine another way of rewriting the original function. Use a graphing utility to rule out incorrectly rewritten functions.
(c) Add a trigonometric term to the original function so that it becomes a perfect square trinomial. Rewrite the function as a perfect square trinomial minus the term that you added. Use the graphing utility to rule out incorrectly rewritten functions.
(d) Rewrite the result of part (c) in terms of the sine of a double angle. Use the graphing utility to rule out incorrectly rewritten functions.
(e) When you rewrite a trigonometric expression, the result may not be the same as a friend's. Does this mean that one of you is wrong? Explain
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