Solve 1+1+2/(1-tan²x )-(3-tan²x)/(1-3 tan²x )=0
Prove that:tan-11/3+tan-11/5+tan-11/7+tan-11/8=45°
Prove that:(sin75°+sin15°)/(sin75°-sin15°)=tan60°
Transform the difference of two squares into a rectangle, the ratio of two sides being 2 : 3.
Evaluate to four significant figure by logarithm,
Simplify yz(x+a)/(x-y)(x-z)+zx(y+a)/(y-z)(y-x)+xy(z+a)/(z-x)(z-y)
求证:(sinα+sinβ)/sin(α+β)=cos((α-β)/2)/cos((α+β)/2)
计算:sin 4π/3∙cos 25π/6∙tg(-3π/4).
已知x+x-1=2cosθ,求证:xn+x-n=2cosnθ.
记函数f(x)=sin(ωx+π/4)+b(ω>0)的最小正周期为T.若2/3 π<T<π,且y=f(x)的函数图像关于点(3π/2,2)中心对称,则f(π/2)=【 】
设函数f(x)=sin(ωx+π/3)在区间(0,π)恰有三个极值点、两个零点,则ω的取值范围是【 】
将函数f(x)=sin(ωx+π/3) (ω>0)的图像向左平移π/2个单位长度后得到曲线C,若C关于y轴对称,则ω的最小值是【 】