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Q.
A circular wire of radius $7\,cm$ is cut and bend again into an arc of a circle of radius $12\,cm$. The angle subtended by the arc at the centre is
Trigonometric Functions
Solution:
Circumference of a circular wire of radius $7 \,cm$
$=2\pi \times 7 = 14 \pi$
As we know $\theta=\frac{l}{r}$
$\Rightarrow \theta=\frac{14\pi}{12}$
$=\frac{7\pi \times 180^{\circ}}{6\pi}=210^{\circ}$.