化简:sin^2(75°)*cos^2(15°)-cos^2(75°)*sin^2(15°)
(cos^2)15°+(sin^2)15°等于多少
(cos^2)15°-(sin^2)15等于多少
化简:根号1+2sin(40°)cos(40°)
化简cos^2(-α)-[tan(360°+α)/sin(-α)]
化简cos(15°+a)sin(45°+a)-cos(75°-a)sin(45°-a)
2sin@+cos@等于?
化简cos^2(a+15)+sin^2(a-15))+sin(a+180)cos(a-180)
化简~cos^2(a+15)+sin^2(a-15)+sin(a+180)cos(a-180)
化简:1+sinθ+cosθ+2sinθcosθ /1+sinθ+cosθ
Sin^2 45°+cos^2 45°=?
sin^2 80°等于 cos^2 10°?
sinΘ-2cosΘ=0,Θ属于(0.,90°),求sinΘ、cosΘ的值.