由题意可得:
sin(A+B)/cos(A-B)=(sinAcosB+cosAsinB)/(cosAcosB+sinAsinB)
上下两式同时除以cosAcosB(cosAcosB不等于0)可得:
sin(A+B)/cos(A-B)=(tanA+tanB)/(1+tanAtanB)
又tanA+tanB=6,tanAtanB=7代人可得:
sin(A+B)/cos(A-B)=6/8=3/4
由题意可得:
sin(A+B)/cos(A-B)=(sinAcosB+cosAsinB)/(cosAcosB+sinAsinB)
上下两式同时除以cosAcosB(cosAcosB不等于0)可得:
sin(A+B)/cos(A-B)=(tanA+tanB)/(1+tanAtanB)
又tanA+tanB=6,tanAtanB=7代人可得:
sin(A+B)/cos(A-B)=6/8=3/4