The area of the base of a right circular cylinder is $$ 616 cm^2 $$ and its height is $$2.5$$ cm. find the curved surface area of the cylinder.
$$\pi r^2 = 616$$
$$r^2 = \dfrac{616\times 7}{22}$$
$$r^2 = 28\times 7$$
$$r = \sqrt{196}$$
$$r = 14$$
$$C.S.A = 2\pi rh$$
$$2 \times \dfrac{22}{7} \times 14 \times 2.5$$
$$= 220cm^2$$