Установить тождественное соответствие
1. $$1-\cos^2\alpha$$
2. $$2\sin\alpha\cos\alpha$$
3. $$\cos^2\alpha-\sin^2\alpha$$
4. $$\cos^4\alpha+\sin^2\alpha\cos^2\alpha$$
А. $$\cos^2\alpha$$
Б. $$\cos2\alpha$$
В. $$\sin2\alpha$$
Г. $$-\cos2\alpha$$
Д. $$\sin^2\alpha$$
Решение
1. $$1-\cos^2\alpha=\sin^2\alpha$$ – Д
2. $$2\sin\alpha\cos\alpha=\sin2\alpha$$ – В
3. $$\cos^2\alpha-\sin^2\alpha=\cos2\alpha$$ – Б
4. $$\cos^4\alpha+\sin^2\alpha\cos^2\alpha=\cos^2\alpha(\cos^2\alpha+\sin^2\alpha)=\cos^2\alpha$$ – А
Ответ: 1-Д; 2-В; 3-Б; 4-А