因为tan(-a)=-tana, tan(π+a)=tana已知tan(-a-4π/3)=-tan(-a-4π/3)=-5,则tan(4π/3+a)=5tan(4π/3+a)=5tan(π+π/+a)=5所以,tan(π/3+a)=5
解tan(-a-4π/3)=tan[-(a+4π/3)]=-tan(a+4π/3)=-tan(a+π+π/3)=-tan(a+π/3)=-5 ∴tan(a+π/3)=5