Question

The angle subtended at the centre of a circle of radius $3cm$ by an arc of length $1cm$ is:

• A. $\frac{{30}^o}{\pi }$
• B. $\frac{{60}^o}{\pi }$
• C. ${60}^o$
• D. None of the above

Answer 1

Answer: (B)

$\frac{{60}^o}{\pi }$

Angle subtended at the centre of circle is $\theta =\frac{l}{r}$

$\Rightarrow \theta =\frac{1}{3}$

Now, $\pi$ radian $={180}^o$

$\Rightarrow \frac{1}{3}$ radian $={180}^o\times \frac{1}{3\pi }=\frac{{60}^o}{\pi }$

Hence, option B is correct.