Question

Find the area of circular ring whose inner and outer radii are 16 cm and 19 cm

Answer 1

Given that Area of the Inner radii of the ring r = 16cm.

Given that Area of the outer radii of the ring R = 19cm.

We know that Area of the ring = $\pi R^2 - \pi r^2$

                                                   = $\pi (R^2 - r^2)$

                                                   = $\pi [(19^2 - 16^2)]$

                                                   = $\frac{22}{7} [(19 + 16)(19 - 16)]$

                                                   = $\frac{22}{7} * 35 * 3$

                                                   = 22 * 5 * 3

                                                   = 330cm^2.


Therefore the area of the circular ring = 330cm^2.


Hope this helps!

Answer 2

Outer area-Inner area = total area
22÷7×19×19 -22÷7×16×16
1134.571 - 804.5714 = 329.9996