if sin a = 3/5 in II cos a = -4/5 if sin b = 5/13 in I cos b = 12/13 sin(a+b) = sina cosb + cosa sinb = (3/5)(12/13) + (-4/5)(5/13) = (36 - 20)/65 = 16/65
You can ask a new question or answer this question.