Tìm góc lượng giác \(x\) sao cho:

cos(x + 50°) = \(\frac{1}{2}\);

Do \(\cos 60^\circ = \frac{1}{2}\) nên cos(x + 50°) = \(\frac{1}{2}\)⇔ cos(x + 50°) = cos 60°

\( \Leftrightarrow \left[ \begin{array}{l}x + 50^\circ = 60^\circ + k360^\circ \\x + 50^\circ = - 60^\circ + k360^\circ \end{array} \right.\left( {k \in \mathbb{Z}} \right)\)

\( \Leftrightarrow \left[ \begin{array}{l}x = 10^\circ + k360^\circ \\x = - 110^\circ + k360^\circ \end{array} \right.\left( {k \in \mathbb{Z}} \right)\).