tan^2a=2tan^2⊙+1求证sin^2⊙=2sin^2a-1

求证[1]1-2sin acos a/cos²a -sin²a =1-tan a/1+tan a.[ 求证：tan a/2＝(1-cos)/sin a=sin a/(cos a+1) 已知tan^2A=2tan^B+1求证sin^2B=2sin^2A-1 已知sin^2B=2sin^2A-1求证tan^2A=2tan^B+1 已知tan^2 a=2tan^ B +1,求证sin^2 b=sin^2 a -1 已知tan(A-B)/tanA+sin^2C/sin^2A=1,求证：tanA*tanB=tan^2C 已知tan(a-r)/tana+sin^2b/sin^2a=1 ,求证tan^2b=tana*tanr.. tan^2a =2tan^2b+1 求证 cos2a +sin^2b=0 求解 已知 sin(a+b)=1/2 ,sin(a_b)=1/3,求证:tan a=5tan b 证明：(1+tan a+cot a)/(1+tan^2 a+tan a)-cot a/(1+ tan^2 a)=sin 求证1/（sin^2)a+1/(cos^2)a-1/(tan^2)a=2+(tan^2)a 问几道高中三角函数题1、求证：tanα*sinα/(tanα-sinα)=(tanα+sinα)/tanα*sinα2、