Answer:
[tex]\theta=\dfrac{7}{4}\ \text{radian}[/tex]
Step-by-step explanation:
We have,
Radius of the circle is 12 cm
Arc length, l = 21 cm
It is required to find the central angle of the circle. The formula for the length of an arc of a circle is :
[tex]l=r\times \theta[/tex]
[tex]\theta[/tex] is central angle
[tex]\theta=\dfrac{l}{r}\\\\\theta=\dfrac{21}{12}\\\\\theta=\dfrac{7}{4}\ \text{radian}[/tex]
So, the angle at the centre of the circle is [tex]\dfrac{7}{4}\ \text{radian}[/tex].
