Consider the function defined on the interval .

MATHEMATICS · Multi-part · AP · Calculus AB · Analytical Applications of Differentiation · Analytical Applications of Differentiation

Problem

Consider the function h(x)=sin⁡x−xcos⁡xh(x)=\sin x- x\cos x defined on the interval 0<x<2π0< x <2\pi. (i) Show that h′(x)=xsin⁡xh'(x)=x\sin x and hence find all values of xx in (0,2π)(0,2\pi) for which h′(x)=0h'(x)=0. (ii) Obtain an expression for h′′(x)h''(x). (iii) For each stationary point found in part (i), decide whether it is a point of local maximum or local minimum. Write the corresponding ordered pairs (x,h(x))(x,h(x)) using exact values. (iv) State which, if any, of these stationary points gives the greatest value of hh on (0,2π)(0,2\pi).

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