Lösung 4.3:3c
Aus Online Mathematik Brückenkurs 1
(Unterschied zwischen Versionen)
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| - | {{ | + | With the help of the Pythagorean identity, we can express |
| - | < | + | <math>\cos v</math> |
| - | {{ | + | in terms of |
| + | <math>\text{sin }v</math>, | ||
| + | |||
| + | |||
| + | <math>\cos ^{2}v+\sin ^{2}v=1</math> | ||
| + | |||
| + | |||
| + | In addition, we know that the angle | ||
| + | <math>v</math> | ||
| + | lies between | ||
| + | <math>-{\pi }/{2}\;</math> | ||
| + | and | ||
| + | <math>{\pi }/{2}\;</math>, i.e. either in the first or fourth quadrant, where angles always have a positive | ||
| + | <math>x</math> | ||
| + | -coordinate (cosine value); thus, we can conclude that | ||
| + | |||
| + | |||
| + | <math>\cos v=\sqrt{1-\text{sin}^{2}\text{ }v}=\sqrt{1-a^{2}}</math> | ||
Version vom 10:58, 29. Sep. 2008
With the help of the Pythagorean identity, we can express \displaystyle \cos v in terms of \displaystyle \text{sin }v,
\displaystyle \cos ^{2}v+\sin ^{2}v=1
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
\displaystyle x
-coordinate (cosine value); thus, we can conclude that
\displaystyle \cos v=\sqrt{1-\text{sin}^{2}\text{ }v}=\sqrt{1-a^{2}}
