证明cos^2θ(1-tan^2θ)=cosθ
证明1-2cos^2θ/tanθ-cotθ=sinθcosθ
证明cos^2θ(1-tan^2θ)=cosθ
证明下列恒等式tan^2 θ *(1-sinθ)/(1+cosθ)=(1-cosθ)/(1+sinθ)
证明下列恒等式(sinθ+cosθ)/(1-tan^2θ)+sin^2θ/(sinθ-cosθ)=sinθ+cosθ
|cosθ|=-cosθ,tanθ
已知tan(θ+π/4)=-2,求cosθ平方+sinθcosθ-1
sin^2θ/sinθ-cosθ + cosθ/1-tanθ = sin^2θ/sinθ-cosθ + cosθ/1-(
证明tanα/2=1-cosɑ/sinɑ
证明tan a/2=sin a/(1+cos a)
tanθ+cosθ=1那么(tanθ)^2+(cotθ)^2=?
证明1/cos^α-tan^2α-sin^2α=cos^2α
证明tanα-cotα=(1-2cos^2α)/(sinαcosα)