Ushtrimi 2

Vërtetoni identitetet e mëposhtme:

a) $\text{tg}A + \text{cotg}A \equiv 2 \text{ cosec}2A$

b) $\text{cosec}2A + \text{cotg}2A \equiv \text{cotg}A$

c) $2 \text{ cosec}2A \equiv \sec A \text{ cosec}A$

d) $\text{cosec}A - \text{cotg}A \equiv \text{tg}\frac{A}{2}$