$\tan \beta=\frac{q}{p}$ হলে $\cos 2 \beta$ এর মান কত ?

$\frac{2 p q}{p^{2}-q^{2}}$

$\frac{2 p q}{p^{2}+q^{2}}$

$\frac{p^{2}-q^{2}}{p^{2}+q^{2}}$

$\frac{p^{2}+q^{2}}{p^{2}-q^{2}}$