三角函数3已知tana,tanb是方程x平方+3根号下3x+4=
已知tana,tanb是方程x平方+3根号下3x+4=0的两根,且a,,b∈（-Π/2,Π/2),求a+b的值.
tana + tanb = -3根号3 tanatanb = 4 tan(a+b) = (tana + tanb)/(1-tanatanb) =(-3根号3)/(1-4) = 根号3 a,,b∈（-Π/2,Π/2) ====>a+b∈（-Π,Π) a+b = Π/3 或 -2Π/3