1 (1)Let {xk}nk=1?(0,π) , and define x=1n∑k=1nxi. Show that ∏k=1nsinxkxk≤(sinxx)n. Proof. Direct computations show (lnsinxx)′′=(lnsinx?lnx)′′=?1sin2x+1x2<0, for all x∈(0,π) . Thus lnsinxx is a concave function in (0,π) . Jensen's inequality then yiel