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Question : In the given figure, the length of arc AB is equal to twice the length of radius $r$ of the circle. Find the area of sector OAB in terms of the radius $r$.

Option 1: $3r$

Option 2: $2r$

Option 3: $ \pi r^2$

Option 4: $ r^2$


Team Careers360 10th Jan, 2024
Answer (1)
Team Careers360 22nd Jan, 2024

Correct Answer: $ r^2$


Solution : Let the radius of the circle be $r$
Here, we know that the length of the arc = $2r$
$⇒ l = r × \theta$
Where $\theta$ is in radian and $l$ is the length of the arc.
$⇒ 2r = r × \theta$
$⇒ \theta = 2$
Area of the sector = $\frac{\theta}{360} \times \pi r^2$ 
Area of the sector = $\frac{2}{360} × 180 × r^2$ [As $\pi = 180°$] 
Area of the sector = $r^2$
Hence, the area of the sector OAB in terms of the radius is $r^2$.
Hence, the correct answer is $r^2$.

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