1/cos^2A=1+tan^2A是什么意思
为什么 tan a +1/tan a=sin^2 a +cos^2 a/(sina cos a)
证明tan a/2=sin a/(1+cos a)
证明:cos^4 a-sin^4 a=cos^2 a(1-tan a)(1+ tan a)
tan a/2=sin/1+cos a=1-cos a/sin a
求证:tan a/2=(1-cos)/sin a=sin a/(cos a+1)
求证[1]1-2sin acos a/cos²a -sin²a =1-tan a/1+tan a.[
求证1/(sin^2)a+1/(cos^2)a-1/(tan^2)a=2+(tan^2)a
求证:sin^2A+cos^2A+sinAcosA/sin^2A+cos^2A=tan^2A+1+tanA/tan^2A
tan a/2=(1-cos a)/sin a=sin a/(1+cos a)如何证明?
已知tan a=-1/3,求4sin a-2cos a/5cos a+3sin a=
tan a+1 /1-tan a =3+2√2,求sin a和cos a的值.
若sin a×cos a=1/2,则tan a+cos a/sin a的值