Question

已知tana=4√3 ,cos(a+b)=-11/14,且0°

Answer 1

60du

tana=4√3,sina/cosa=4√3,cosa=1/7

cos(a+b)=cosa*cosb-sina*sinb=-11/14

cosb-4√3sinb=-11/2

因为sinb*sinb+cosb*cosb=1

cosb=1/2

b=60