Lösung 4.3:7b
Aus Online Mathematik Brückenkurs 1
Using the addition formula, we rewrite \displaystyle \sin (x+y) as
If we use the same solution procedure as in exercise a, we use the Pythagorean identity \displaystyle \cos^2\!v + \sin^2\!v = 1 to express the unknown factors \displaystyle \sin x and \displaystyle \sin y in terms of \displaystyle \cos x and \displaystyle \cos y,
The angles x and y lie in the first quadrant and both \displaystyle \sin x and \displaystyle \sin y are therefore positive, i.e.
Thus, the answer is
