4. Nora is certain that cos(x + #2) = sinx. She is mistaken. Note: The unit circle could be very helpful in thinking about why Nora is mistaken and about the next questions. The graphs could also be very helpful. a. Show clearly that she is mistaken.* b. Now use another method to show her why she is mistaken. c. Write an equation that relates the sin and cosine functions that is correct. d. Explain how you can check that your equation is correct. "Remember: you can show something is not always true by giving a counterexample