若a∈(-pi,-pi/2),且tan a=3/4,则sina=?
f(a)=sin(pi-a)cos(2pi-a)tan(-a+3pi/2)/cos(-pi-a) 求 f(-31pi/3
tana=2求sin(pi-a)cos(2pi-a)sin(-a+3pi/2)/tan(-a-pi)sin(-pi-a)
已知cosa=3/5,且a属于(3pi/2,2pi),则cos(a-pi/3)=
已知a为锐角,且tan(pi/4+a)=2(1)求tana的值(2)求sin2acosa-sina/cos2a的值
tan(5+a)=-2,且cos>0,则sin(-pi+a)=?/
若cos(2pi-a)=24/25,且(3/2)pi
tanθ=a,求[sin(pi/4+θ)/sin(pi/2-θ)]*tan2θ
tanθ=a,求[sin(pi/4+θ)/sin(pi/2-θ)]*tan2θ,
a,b∈(3pi/4,pi),sin(a+b)=-3/5,sin(b-pi/4)=12/13,则cos(a+pi/4)=
已知sinA+cosA=1/3,A 属于(0,pi),求cos(A-pi/3)+cotA
已知a锐角 且sin(a-pi/6 )=1/3 求sina
sina=5/4,那么sin(a+4/pi)-二/根号2•cos(pi-a)=