How do I find the exact value for the trigonometric express cos(u+v) given that sin u= 3/5, where u is in quadrant 2 and cos v= 15/17, where v is in quadrant 1

Answer 1

sin u = 3/5 ⇒ cos -4/5 in QII by Pythagoras

cos v = 15/17 ⇒ sin v = 8/17 in QI also by Pythagoras

You now have all values to use the sum formula.