We have, 180° = π Radians ∴ 1° = $\left(\frac{\pi}{180}\right)$ radians (i) 25° = $\left(\frac{\pi}{180} \times 25\right)$ radians = $\frac{5\pi}{6}$ radians (ii) As we know, 30' = $\left(\frac{30}{60}\right)^{\circ}$ = $\left(\frac{1}{2}\right)^{\circ}$ ∴ - 47° 30' = - $\left(47\frac{1}{2}\right)^{\circ}$ = - $\left(\frac{95}{2}\right)^{\circ}$ ⇒ - $\left(\frac{95}{2}\right)^{\circ}$ = - $\left(\frac{95}{2} \times \frac{\pi}{180}\right)$ radians = $\frac{-19\pi}{72}$ radians (iii) 240° = $\left(\frac{\pi}{180} \times 240\right)$ radians = $\frac{4\pi}{3}$ radians (iv) 520° = $\left(\frac{\pi}{180} \times 520\right)$ radians = $\frac{26\pi}{9}$ radians