Marirea liniară transversală

$$ \displaylines { \tan{i} = \frac{y_1}{- x_1} \quad \tan{i} \simeq \sin{i} \implies \sin{i} = \frac{y_1}{- x_1} \\ \tan{r} = \frac{- y_2}{x_2} \quad \tan{r} \simeq \sin{r} \implies \sin{r} = \frac{-y_2}{x_2} \\ \\ \frac{ \sin{r} }{ \sin{i} } = \frac{- y_2}{y_1} \cdot \frac{-x_1}{x_2} \implies \bf{ \beta = \frac{x_2 n_1}{x_1 n_2} } } $$