Question

已知tan(a-3分之派) =-根号3/5,则sinacosa/（3cos^2a-2sin^a）=

Answer 1

tan(a-π/3)=(tana-√3)/(1+√3*tana)=-√3/5

∴5tana-5√3=-√3-3*tana

∴tana=√3/2

∴sinacosa/（3cos^2a-2sin^a）=tana/(3-2tan²a)=(√3/2)/(3-3/2)=√3/3