3-cos 20°/2-sin ^2 80°等于
sin^2 80°等于 cos^2 10°?
2sin@+cos@等于?
(cos^2)15°+(sin^2)15°等于多少
(cos^2)15°-(sin^2)15等于多少
sin^2是什么,sin^260°等于什么,还有cos^43兀/2等于什么
sin@2-cos@2等于
Cos(&-3派/2)等于Sin&还是-Sin&?
(cos^2 10°-cos^2 80°)+sin^2 20°
计算[3/(sin^2)20°-[1/(cos^2)20°]+64(sin^2)20°
sin+cos小于等于根号2
1/2sin α cos α 为什么等于sin α
根号下sin²150°+cos²35°+2sin210°cos²145° 等于?