Question 23

loading...

Prev/Next links

Jambmaths question: 

An arc of a circle subtends an angle of 30oon the circumference of radius 21cm. Find the length of the arc. [take $\pi =\tfrac{22}{7}$]

Option A: 

11cm

Option B: 

22cm

Option C: 

33cm

Option D: 

44cm

Jamb Maths Solution: 

$\begin{align}  & \angle AOB=\angle ACB\text{   }\{angle\text{ }at\text{ }centre=2\times angle\text{ }at\text{ }circum\} \\ & \angle AOB=2\times {{30}^{\text{o}}}={{60}^{\text{o}}} \\ & \text{Length of arc }ACB=\frac{\theta }{360}\times 2\pi r \\ & =\frac{60}{{{360}^{\text{o}}}}\times 2\times \frac{22}{7}\times 21cm \\ & =22cm \\\end{align}$

Jamb Maths Topic: 
Year of Exam: