Shkruani secilën prej shprehjeve si një raport trigonometrik të vetëm.

a) $2 \sin 23^{\circ} \cos 23^{\circ}$

b) $\cos^2 42^{\circ} - \sin^2 42^{\circ}$

c) $\frac{2 \operatorname{tg} 70^{\circ}}{1 - \operatorname{tg}^2 70^{\circ}}$

d) $2 \cos^2 50^{\circ} - 1$

e) $2 \sin 3\alpha \cos 3\alpha$

f) $\sin \alpha \cos \alpha$

g) $\frac{1}{2}(1 + \cos 40^{\circ})$

h) $1 - 2 \sin^2 4\alpha$

i) $1 + \cos 2\alpha$

j) $\frac{1}{2}(1 - \cos 50^{\circ})$

k) $\cos^2 \frac{\pi}{5} - \sin^2 \frac{\pi}{5}$

l) $\sec \alpha \operatorname{cosec} \alpha$

m) $\cot \alpha - \operatorname{tg} \alpha$

n) $\frac{1 - \operatorname{tg}^2 4\alpha}{2 \operatorname{tg} 4\alpha}$