Question

2. Find the area of the circles, given that: (a) radius = 20 cm
(b) diameter = 42 cm
​

Answer 1

⠀⠀⠀⠀

$\sf{\bold{\blue{\underline{\underline{Given}}}}}$

●a. radius =20cm.⠀

●b. diameter=42cm.⠀⠀⠀

$\sf{\bold{\red{\underline{\underline{To\:Find}}}}}$

■ Find the area of the two circle a&b.⠀⠀⠀⠀

$\sf{\bold{\purple{\underline{\underline{Solution}}}}}$

a. In the situation a,

radius(r)=20cm.

so,Area =${\pi r^2}$⠀⠀⠀

$\implies{\frac{22}{7}×20^2}$

$\implies{\frac{22}{7}×20×20}$

$\boxed{\pink{\frac{8800}{7}cm^2}}$

b. in the situation B,

Diameter (2r)=42cm

radius(r)=$\frac{42}{2}=21$

so, Area=${\pi r^2}$

$\implies{\frac{22}{7}×21^2}$

$\implies{\frac{22}{\cancel{7}}×\cancel{21}×21}$

$\implies{22×3×21}$

$\boxed{\pink{1386cm^2}}$

$\sf{\bold{\green{\underline{\underline{Answer}}}}}$

⠀⠀⠀⠀

Area of

A.$\orange{\frac{8800}{7}cm^2}$

B.$\orange{1386cm^2}$

⠀⠀⠀⠀

Answer 2

Answer:

a)Area is 1256.637 sq cm

b)Area is 1385.4 sq cm

Step-by-step explanation:

Given that

a) Radius of circle is 20cm

b) Diameter of circle is 42cm

To find

Area of circle

Solution

a)As we know that

$area \: of \: circle = \pi \times {radius}^{2}$42

hence

$\pi = 3.14$

we get

$area \: of \: circle = 3.14 \times {20}^{2}$

by multiplication we get

$area \: of \: circle = 1256.637 {cm}^{2}$

b) Diameter is 42cm

We know that radius is always half of diameter hence

$radius = \frac{diamete}{2} = \frac{42}{2} = 21cm$

now

$area \: of \: circle = \pi \times {21}^{2}$

by multiplication we get

$area \: of \: circle = 1385.44 {cm}^{2}$