Question

设a=sin15°+cos15°,b=sin16°+cos16°,则下列各式中正确的是(    )

A.a＜＜b                         B.b＜＜a

C.b＜a＜                         D.a＜b＜

Answer 1

D

解析:∵a=sin15°+cos15°=sin60°＞sin45°=1,

b=sin16°+cos16°=sin61°.

∴1＜a＜b.∴a²+b²＞2ab＞2b＞2a.∴＞b＞a.