设a=(√2)/2(sin17+cos17),b=2cos213-1,c=(√3)/2,求a,b,c大小?

设a=(√2)/2(sin17+cos17),b=2cos213-1,c=(√3)/2,求a,b,c大小?

a=(√2)/2(sin17+cos17)
=sin17°*cos45°+cos17°*sin45°
=sin(17°+45°)
=sin62°
b=2cos²13°-1
=cos(2*13°）
=cos26°
=sin64°
c=(√3)/2
=sin60°
sin60°