Help please with these

4. The first derivative of the function f is given by f'(x) = sin x - How many critical values does f have on the 9 open interval (0, 10) ?7. Given f ' (x) = 2sin*(2.x) - 3sin (4x), over the open interval (0, 0.7), at what value of x is the tangent line to f horizontal? A. 0.390 B. 0.555 C. 0.368 D. 0.567 E. 0.195 8. Given f ' (x) = 2sin*(2.x) -3sin (4.x), at which x-value over the interval (0, 2] does the graph of f have a relative minimum? A. 1.938 B. 1.146 C. 0.368 D. 1.571 E. 0.56710. A rectangle with one side on the xaxis has its upper vertices on the graph of y = COS x as shown in the gure below. What is the maximum area afthe rectangle? A. 0.360 B. 0.982 C. 1.122 0. 3.426 E. 6. 577 13. A particle moves along the xaxis so that at time t 2 0 its position is given by x(t) : cos-J; . What is the velocity of the particle at the first instance the particle is at the origin