cos(45+30)cos(45-30)+sin(45+30)sin(45-30=)
sin(x+30)*cos(x+45)
(cos 45°-sin 30°)/(cos 45°+sin 30°)
sin(45-3x)*cos(60-3x)-cos(30+3x)*sin(45+3x)
sin(45-3x)*cos(60-3x)-cos(30+3x)*sin(45+3x) ?
[sin(45°+θ)]/[cos(45°-θ)]-[cos(θ+60°)]/[sin(θ+30°)]=?
2cos 30°-2sin 60°·cos 45°=?
cos tan sin 30° 45° 60°是多少
√(cos 60°-1)²+2√cot 45°-sin 60°+|sin 30°-1|=?
sin(45/2)/cos(45/2)=?
求sin cos tan 30 45 60 90 反正到180度的值,如sin 30是2/1
证明tan(45+α)=cosα+sinα/cosα-sinα
已知sin a+cos a=m求cos a-sin a(45