Energija i zakon očuvanja energije - 4.

$0^{\circ }\le \alpha \le {90}^{\circ }0^\{\backslash circ\}\; \backslash leq\; \backslash alpha\; \backslash leq\; 90^\{\backslash circ\}$

$\alpha ={90}^{\circ }\backslash alpha=90^\{\backslash circ\}$