a=√2/2(sin17°+cos17°) = sin17°cos45°+cos17°sin45° = sin(17+45)°=sin62°b = 2(cos13°)^2-1 = cos2*13°=cos26°=cos(90°-64°)=sin64°c =√3/2 = sin60°因为 sinx在第一象限是增函数,有sin64°>sin6...