19
收起
tana=2tana/2 / (1-tan^2 a/2)=2*2/(1-2^2)=-4/3tan(a+π/4)=(tana+tanπ/4)/(1-tanatanπ/4)=(-4/3+1)/(1+4/3)=-1/76sina+cosa/3sina-2cosa=(6tana+1)/(3tana-2)=(-8+1)/(-4-2)=7/6