Question

radius of semicircle is 21cm find it's area

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Answer 1

Answer:

693$cm^{2}$ is the answer

Step-by-step explanation:

Radius of semicircle =   π$\frac{ R^{2}}{2}$

R = 21

[$\frac{22}{7}$ * $21^{2}$ ] / 2

[$\frac{22}{7}$ * 441 ] / 2

• 7 multiplied by 63 is 441 , so 7 cancels and 441 becomes 63

∴  [ 22 * 63 ] / 2

• 2 multiplied by 11 is 22 , so 2 cancels and 22 becomes 11

∴ 11 * 63

       = 693$cm^{2}$ is the area of the semicircle

• HERE THE VALUE OF  π ( pie ) IS TAKEN AS $\frac{22}{7}$

• IF YOU TAKE THE VALUE OF π ( pie ) AS 3.14 THEN YOUR ANSWER WILL BE  692.37
• WHEN YOU ROUND OF THE NUMBER YOU WILL GET 693 .

hope this helps you

Answer 2

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• Radius = 21cm

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• Area of semicircle = ?

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❍ Formula Used :

• ${\underline{\boxed{\pmb{\pmb{\sf{ \: \sf \:Area_{(Semicircle)}=\dfrac{1}{2}×\dfrac{22}{7}×r^2 }}}}}}$

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$\begin{gathered} \\ \qquad \; \dashrightarrow \sf{ Area_{(Semicircle)}=\dfrac{1}{2}×\dfrac{22}{7}×r^2}\end{gathered}$

$\begin{gathered} \\ \qquad \; \dashrightarrow \sf{ Area_{(Semicircle)}=\dfrac{1}{2}×\dfrac{22}{7}×21 {}^{2} }\end{gathered}$

$\begin{gathered} \\ \qquad \; \dashrightarrow \sf{ Area_{(Semicircle)}=\dfrac{1}{ \cancel{2}}×\dfrac{ \cancel{22}}{7}×21 \times 21}\end{gathered}$

$\begin{gathered} \\ \qquad \; \dashrightarrow \sf{ Area_{(Semicircle)}=\dfrac{11}{7}×21×21}\end{gathered}$

$\begin{gathered} \\ \qquad \; \dashrightarrow \sf{ Area_{(Semicircle)}=\dfrac{4851}{7} }\end{gathered}$

$\begin{gathered} \\ \qquad \; \dashrightarrow \sf{ Area_{(Semicircle)}=693cm \: \: \: }\end{gathered}$

$\begin{gathered} \qquad \; \dashrightarrow \; \; {\underline{\boxed{\color{darkblue}{\pmb{\pmb{\frak { Area_{(Semicircle)}=693cm}}}}}}} \; \bigstar \\ \\ \end{gathered}$

$\begin{gathered}\begin{gathered} \\ \qquad{\rule{200pt}{2pt}} \end{gathered}\end{gathered}$

∴ Area of the semicircle is 693cm^2.

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