Question

Треба спростити вираз

Answer 1

$\dfrac{1}{1+cos(a)}+ \dfrac{1}{1-cos(a)} = \dfrac{1-cos(a)+1+cos(a)}{(1+cos(a))(1-cos(a))} =\\\\= \dfrac{2}{1-cos^2(a)} = \dfrac{2}{sin^2(a)}$