求证:3-2cos^2a=3tan^2a+1/tan^2a+1

求证:3-2cos^2a=3tan^2a+1/tan^2a+1 求证tan(3a/2)-tan(a/2)=【2sin（a/2）】/【cos（3a/2）】 已知锐角a,b满足,sinb=2cos(a+b)sina,求证:tan(a+b)=3tan(a) 求证3-sin^4a-cos^4a/2cos^a=1+tan^a+sin^a 速答 谢谢 求证tan(2π-a)cos(3π/2 -a)cos(6π -a) / sin(a+3π/2)cos(a+3π/2) = -tan求证tan(2π-a)cos(3π/2 -a)cos(6π -a) / sin(a+3π/2)cos(a+3π/2) = -tan 求证：tan a/2＝(1-cos)/sin a=sin a/(cos a+1) 求证(cos^2 A)/{[1/tan(a/2)]-tan(A/2)=(sin2A)/4 求证(1-tan^4A)cos^2A+tan^2A=1.. 求证:2sin(a-3π/2)cos(a+π/2)-1/1-2sin^(π+a)=tan(9π+a)+1/tan(π+a)-1 【(sin a+cos a)/(sin a-cos a) 】=3,tan (a-b)=2,tan (b-2a)=? tan a=2,(3sin a-cos a)/(2sin a+cos a)= [sin^2(-a)*cos(π+a)]/[tan(2π+a)*tan(π+a)*cos^3(-π-a)]=? 求证 cos^2 a-sin^2 a/1-2sin acos a =1+tan a/1-tan a sin(2a)[cot(a/2)-tan(a/2)]=4cos^2(a)求证, tan a =-1/3 计算1/(2sin a cos a +(cos a )^2) tan a =3求4sin a-2cos a/5cos+3sin a 已知3tan a=2cos a,则1+tan² a=? 求证1/（sin^2)a+1/(cos^2)a-1/(tan^2)a=2+(tan^2)a