Question

(3) If the radius of a circle is 21 cm then the area of the circle is
(A) 1386 sq. cm (B) 1368 sq. cm
(C) 441 sq. cm
(D) 1441 sq. cm​

Answer 1

Answer:

Step-by-step explanation:

Area of a circle of radius r =πr  

2

=1386cm  

2

 

7

22

​  

×r  

2

=1386cm  

2

 

r  

2

=441cm  

2

 

r=21cm

Circumference of a circle of radius r =2πr

Circumference of circle of radius 21cm=2×  

7

22

​  

×21=132cm

Answer 2

Answer:

$\huge \fbox \color{blue} \fbox \color{blue} \underline {\pink {\underline {\purple {\sf {Answer}}}}}$

$\large \mathrm \color{black}{(a) \: {1386cm}^{2} }$

Step-by-step explanation:

$\large \mathrm \color{black}{Given,}$

$\mathrm \color{black}{radius \: r=21cm \: and \: \pi \: = \frac{22}{7} }$

$\large\mathrm \color{black}{Then,}$

$\mathrm \color{black}{Area \: of \: the \: circle = \pi {r}^{2}sq \: unit }$

$\mathrm \color{black}{ = \frac{22}{7} \times 21 \times 21}$

$\mathrm \color{black}{ = 22 \times 3 \times 21}$

$\mathrm \color{black}{ = {1386cm}^{2} }$