(1+根号3tana)(1+根号3tanb)=4
1+根号3(tana+tanb)+3tana*tanb=4
根号3(tana+tanb)+3tanatanb=3
tana+tanb+根号3tanatanb=根号3
tana+tanb=根号3(1-tanatanb)=0
tan(a+b)=(tana+tanb)/(1-tanatanb)=根号3
锐角a.b,则0