求值：sin(10°+x)cos(50°-x)+sin(50°-x)cos(10°+x)

求值：sin(10°+x)cos(50°-x)+sin(50°-x)cos(10°+x) sin(x+105°)cos(x-15°)-cos(x+105°)sin求化简 化简sin(x-25°)sin(65°-x)+cos(x-25°)cos(65°-x)的结果为 化简cos(180°+x)*sin(x+360°)/[sin(-x-180°)*cos(-180°-x)] 【三角恒等变换】cos(33°-x)sin(63°-x)-cos(x+57°)sin(27°+x) sin（sin（sin（sin（x）=cos（cos（cos（cos（x）,X等于多少? 证明：存在实数X,使得SIN x+cos X=60° 化简cos²（-X）-【tan（360°+X）】/【sin（-X）】 sin(1/x)-cos(1/x)/x (x*sin x*cos x)的导数 设f(x)=[2cos^3 x-sin^2 (360°-x)+2sin(90°+x)+1]/2+2cos^2 (180° 已知tan=2,求(cos x+sin x)/(cos x-sin x)+sin^2x