sin(-1000°)=sin(-2×360°-28°)=-sin28°<0,
sin(-1000°)=sin(-2×360°-28°)=-sin28°<0,
证明:(1) sin(360°-α)=-sinα
证明:sin(360°-α)=-sinα
sin(a+360°)=?
sin²1°+sin²2°+sin²89°+sin²88°=
求证sin3°=(sin^2°-sin^1°)/sin1°
为什么根号3sinα+cosα=2sin(α+30°)
sinΘ-2cosΘ=0,Θ属于(0.,90°),求sinΘ、cosΘ的值.
化简sinA+sin(A+120°)+sin(A+240°)=?
sin^2 (0°)+sin^2( 1°)+.+sin^2(90du) 求和
计算:sin²1°+sin²2°+sin²3°...+sin²45°+sin
数列求和 sin²1°+sin²2°+sin²3°+.+sin²88°+sin&