I need help with these questions, especially the 3rd and fourth one. For those, can you break down how you solve them? Trig equations can be quite confusing. Thank you!

Consider the function f (x) - cosa - sin . Find all x-values on the interval |0, 27] for which there is a horizontal tangent. f(x) = cosx - sin xPOSSIBLE POINTS: 3 Use the derivatives of sin(x) and cos(x) and the trigonometric identities to PROVE that sec(x) - sec(x) tan(I). You must show all steps for full credit. EBIYEEreece POSSIBLE POINTS: 2 A restaurant in Naples, Florida, is very busy during the winter months and extremely slow over the summer. But every year the restaurant grows in sales. odogoboredomextomyears, the revenue R, in uses of $10,000, is projected to follow the model R = R(t) = sint + 0.3t + 1 for 0