Question

Use the given information to evaluate sin (a+b). Exact answers only. No decimals.

Tan a = 4/3, cos b ='-12/13; neither a nor b are in quadrant III.

Answer 1

since cosb < 0, b is in QII, so

sina = 4/5
cosa = 3/5

sinb = 5/13
cosb = -12/13

Now just evaluate

ain(a+b) = sina cosb + cosa sinb