Question

Find the radian measure of $25^°$ and $-47^°\, 30'$ respectively,

• A. $5\pi/36$, $-19\pi /72$
• B. $7\pi/36$, $17\pi /72$
• C. $5\pi/36$, $\pi /72$
• D. $7\pi/36$, $\pi /72$

Answer 1

Answer: (A)

(i) We know that
Radian measure $=\frac{\pi}{180}\times$ Degree measure
$\therefore $ Required radian measure $=\frac{\pi}{180}\times25=\frac{5\pi}{36}$
(ii) We have, $-47^{\circ}30'=-\left[47^{\circ}+\left(\frac{30}{60}\right)^{\circ}\right]=\left(\frac{95}{2}\right)^{\circ}$
Now, required radian measure $=-\left(\frac{\pi}{180}\times \frac{95}{2}\right)=\frac{-19\pi}{72}$