$f(\alpha) f(\beta)-g(\alpha) g(\beta)+1=0$ হলে প্রমাণ কর যে, $1+\frac{g(\alpha)}{f(\alpha)} \cdot \frac{f(\beta)}{g(\beta)}=0$

দেখাও যে, $16 \mathrm{~g}\left(\frac{2 \pi}{15}\right) \mathrm{g}\left(\frac{4 \pi}{15}\right) \mathrm{g}\left(\frac{8 \pi}{15}\right) \mathrm{g}\left(\frac{14 \pi}{15}\right)=\mathrm{I}$

প্রমাণ কর যে, $\{\mathrm{f}(\mathrm{x})\}^{3}+\left\{\mathrm{f}\left(\mathrm{x}+480^{\circ}\right)\right\}^{3}+\left\{\mathrm{f}\left(\mathrm{x}+600^{\circ}\right)\right\}^{3}=-\frac{3}{4} \mathrm{f}(3 \mathrm{x})$