1. (coa+aga + sin² a) sin² a;

1. $$(\cos^2 \alpha + ctg^2 \alpha + \sin^2 \alpha) \cdot \sin^2 \alpha = (1 + \frac{\cos^2 \alpha}{\sin^2 \alpha}) \cdot \sin^2 \alpha = \sin^2 \alpha + \cos^2 \alpha = 1$$

Ответ: 1