a=sin(cos210°)和b=sin(sin210°),a,b哪个大210°在第三象限,cos210°= 负值 = - cos30°= √3/2 ≈ - 0.866sin210°= 负值 = - sin30°=1/2 = 0.5而sinx是奇函数 sin(-x) = - sinxa = sin(cos210°) = - sin (cos3...