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La funzione coseno

triangolo rettangolo A B C a b c α β
$$ \begin{aligned} & \cos\alpha = \frac{b}{c} \\ \\ & \cos\beta = \frac{a}{c} \end{aligned} $$

Grafico

La funzione coseno α cos α [°] [rad] 0 90° 180° 270° 360° 0,5π π 1,5π 2π 1 -1

Calcolatrice

Inserisca 1 valore

α = 
α2 = 
cos α = 

Errore: 

 cos α > 1

Errore: 

 cos α < −1
Arrotondare a  /  cifre decimali

Formule

La funzione coseno

triangolo rettangolo A B C a b c α β
$$ \cos\alpha = \frac{b}{c} $$
$$ \cos\beta = \frac{a}{c} $$
$$ \begin{aligned} &\cos(\alpha + \beta) = \\& = \cos\alpha\cos\beta - \sin\alpha\sin\beta \\ \\ &\cos(\alpha - \beta) = \\& = \cos\alpha\cos\beta + \sin\alpha\sin\beta \end{aligned} $$
$$ \begin{aligned} &\cos\alpha + \cos\beta = \\& = 2\cdot\cos\frac{\alpha + \beta}{2}\cdot\cos\frac{\alpha - \beta}{2} \\ \\ &\cos\alpha - \cos\beta = \\& = -2\cdot\sin\frac{\alpha + \beta}{2}\cdot\sin\frac{\alpha - \beta}{2} \end{aligned} $$
$$ \begin{aligned} & \cos 2\alpha = \cos^2\alpha - \sin^2\alpha \\ \\ & \cos(-\alpha) = \cos\alpha \\ \\ & \left|\cos\frac{\alpha}{2}\right| = \sqrt{\frac{1+\cos\alpha}{2}} \end{aligned} $$
$$ \begin{aligned} & \sin^2\alpha + \cos^2\alpha = 1 \\ \\ & \tan\alpha \cdot \cot\alpha = 1 \ \Rightarrow \\ & \cot\alpha = \frac{1}{\tan\alpha} \\ \\ & \tan\alpha = \frac{\sin\alpha}{\cos\alpha} \\ \\ & \cot\alpha = \frac{\cos\alpha}{\sin\alpha} \end{aligned} $$

Valutazione

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