sin(a+b)=sina*cosb+sinb*cosa=1/2
sin(a-b)=sina*cosb-cosasinb=1/3
sina*cosb=5/12 sinb*cosa=1/12
tana/tanb=sina/cosq*sinb/cosb=sina*cosb/cosa8sinb=5
sin(a+b)=sina*cosb+sinb*cosa=1/2
sin(a-b)=sina*cosb-cosasinb=1/3
sina*cosb=5/12 sinb*cosa=1/12
tana/tanb=sina/cosq*sinb/cosb=sina*cosb/cosa8sinb=5