sin^(2)20°+cos^(2)50°+sin20°cos50°

sin^2(20)-sin^2(25)sin(20)+cos^2(50)+cos^2(25)sin20 sin^2(20)+cos^2(50)+sin20sin50 2sin@+cos@等于? sin(10°)+sin(20°)cos(50°)求值 3-cos 20°/2-sin ^2 80°等于 sin^2 20+cos^2 50+sin20cos50=? sin^2 20+cos^2 50+sin20cos50=? sin^2 20+cos^2 50+sin30cos70=? 2*sin(50)*cos(20)等于多少 急 sin^2 30°+cos()=1 求证:sin^2/(sin-cos) - (sin+cos)/(tan^2 -1) =sin+cos sin^2(20°)+cos^(50°)+sin(20°)cos(50°)=?,不要用三个三角函数公式sina+sinb=2sin((a+b)/2)cos((a-b)/2 (cosa)^2 =1/2+1/2*cos2acos(a)cos(b)=1/2*[cos(a+b)+cos(a-b)]这个不能用 (cos^2 10°-cos^2 80°)+sin^2 20° 求值:3/(sin^2 20°)-1/(cos^2 20°)+64sin^2 20° sin^(2)20°+cos^(2)50°+sin20°cos50° sin^2 20°+cos^2 50°+sin30°sin70° 高中三角函数求值sin^2(20°)+cos^2(50°)+sin20°cos50°=? (cos 10)^2+(cos 50)^2-sin 40 * sin 80 怎么算