Question

find the area of ax circular ring whose inner and outer radii are 16 cm and 19cm respectively. ​

Answer 1

Outer radius(R)= 19 cm

Inner radius(r)=16 cm

Area of ring=

πr^2-πr^2

$\frac{22}{7}*19^2-\frac{22}{7}*16^2$

$\frac{22}{7}*19*19-\frac{22}{7}*16*16$

$1134.57-804.57$

$330 cm^2$

Answer 2

Radii of inner ring = 16cm

Radii of outer ring = 19cm

So,

Area of the whole circle ⤵️

$\pi( {r}^{2} - {r}^{2} ) \\ \\ \frac{22}{7} ( {19}^{2} - {16}^{2} ) \\ \\ \frac{22}{7} (361 - 256) \\ \\ \frac{22}{7} \times 105 \\ \\ 22 \times 15 \\ \\ = 330 {cm}^{2}$