Выбери верный вариант

\(\cos \left(\alpha +\alpha \right)=\) [ \(\cos^2 \left(\alpha \right)-\sin^2 \left(\alpha \right)\) | \(2\sin \left(\alpha \right)\cos \left(\alpha \right)\) | \(\cos^2 \left(\alpha \right)+\sin^2 \left(\alpha \right)\) | \(\dfrac{2\tg \left(\alpha \right)}{1-\tg^2 \left(\alpha \right)}\) ].