sina:cos(a/2)=4:5,tg(a/4)=?
sina:cos(a/2)=4:5,tg(a/4)=?
急!数学题!如果tg(a+b)=2/5,tg(b-派/4)=1/4,那么tg(a+派/4)为?
已知sina+sin^2a=1,求3cos^2a+cos^4a-2sina+1
若sina+sin^2a=1,求cos^2a+cos^4a的和
已知[sina(a-π/4)]/cos(π+2a)=根号2,则sina+cosa=?
1+sina=2cos²(派/4-a/2)
sin(a+π/3)+sina= - 4根号3/5,则cos(a+2π/3)
已知sina =3/5 a∈(π/2,π) 求cos(π/4-a)
已知2sina/2·cos(π/2-a/2)=3/4,求sina
已知tanA=2求4sinA-2cos^3A/5sinA+3coaA的值,5sinA^2A+3sinAcoaA-2coa
k=tg(a)
tg a/2化简成sin cos