Question

Find the radian measure of $25^{°}$ and $-47^{°}30^{\prime }$ 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 $=\frac{\pi }{180}\times 25=\frac{5\pi }{36}$
(ii) We have, $-47^{\circ }30^{\prime }=-\left[47^{\circ }+{\left(\frac{30}{60}\right)}^{\circ }\right]={\left(\frac{95}{2}\right)}^{\circ }$
Now, required radian measure $=-\left(\frac{\pi }{180}\times \frac{95}{2}\right)=\frac{-19\pi }{72}$