Lösung 4.3:3c
Aus Online Mathematik Brückenkurs 1
With the help of the Pythagorean identity, we can express \displaystyle \cos v in terms of \displaystyle \sin v,
In addition, we know that the angle \displaystyle v lies between \displaystyle -\pi/2 and \displaystyle \pi/2, i.e. either in the first or fourth quadrant, where angles always have a positive x-coordinate (cosine value); thus, we can conclude that
