Question

The radius of the circle whose arc of length $15cm$ makes an angle of $\frac{3}{4}$ radian at the centre, is

• A. $10cm$
• B. $20cm$
• C. $11\frac{1}{4}cm$
• D. $22\frac{1}{2}cm$

Answer 1

Answer: (B)

Given that, $\mathrm{arc}=15cm$.

$\theta =\frac{3}{4}$ radian
We know that, Angle $=\frac{\text{ Arc }}{\text{ Radius }}$
$\Rightarrow \text{ Radius }=\frac{\text{ Arc }}{\text{ Angle }}=\frac{15\times 4}{3}=20cm$