Evaluate: cosA = 3/5; <A in Quadrant IV, and sinB = -12/13; <A in Quadrant III
1.) sin(A-B)
2.) tan(A+B)
for an angle θ in standard position, with terminal point at (x,y) you have
r^2 = x^2 + y^2
sinθ = y/r
cosθ = x/r
So, now you know that
sinA = -4/5
cosB = -5/13
Now you can find tanA and tanB, and then use the
sum of angles formulas,