求证：tan(2π-a)sin(-2π-a)cos(6π-a)/cos(a-π）sin(5π-a)=-tana

求证:2sin(a-3π/2)cos(a+π/2)-1/1-2sin^(π+a)=tan(9π+a)+1/tan(π+a)-1 求证tan^2asin^2a=tan^2a-sin^2a求证tan^2 a 乘 sin^2 a=tan^2 a-sin^2 a 若a属于(0,π/2)试比较tanα、tan(tanα)、tan(sinα) 三角形ABC中,3SinB=Sin（2A+B）,4tan(A/2)=1-tan²(A/2).求证：A+B=π/4 求证2(cosθ -sinθ )/1+sinθ +cosθ =tan(π/4-θ /2)-tanθ /2 求证sin与tan 已知3sinB=sin(2A+B),求证tan(A+B)=2tanA 求证：（1）tan(a/2+π/4)+tan(a/2-π/4)=2tana (2)1+cos2a+2sin^2a=2 求证:tan(2π-a) sin(-2π-a) cos(6π-a) / cos(a-π) sin(5π-a)=-tana如题, 求证：tan(2π-a)sin(-2π-a)cos(6π-a)/cos(a-π）sin(5π-a)=-tana 1.求证tanαsinα/tanα-sinα=tanα+sinα/tanαsinα2.已知sinα+cosα=-1/5(π/2 求证 cos^2 a-sin^2 a/1-2sin acos a =1+tan a/1-tan a 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) 已知sin(a+β)=1,求证;tan(2a+3β)-tanβ=0 cos²(-a)-sin(-a)/ tan(2π+a)化简 已知 3sin A = sin (2B +A ),求证 ： tan（A+B)= 2tanB 求证:(sin 2x /(1-cos 2x) )·(sin x /(1+sin x))=tan (π/4-x/2). 已知3sinβ=sin(2a+β)求证tan(a+β)=2tan a