Look at the picture below. What is tan(A – B)?
Thanks!

Step-by-step explanation:
the mistake was made when the value of cos 3 pi over 2 was calculated.
tan(A-B)= ?since tan=sin/cos
sin(A-B) = sinAcosB-cosAsinB
cos(A-B) cosAcosB+sinAsinB
divide by cos on the RHS
tan(A-B)= tanA-tanB
1+tanAtanB