Question

The area of circle is 98.55 cm2 .find its circumference
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Answer 1

❏ Using Formula:-

• for a cuboid of dimensions( l×b×h )

1) the diagonal is given by,

$\longrightarrow \sf \boxed{diagonal= \sqrt{l {}^{2} + b {}^{2} + h {}^{2} } }$

2)volume of the Cuboid

$\longrightarrow \sf\boxed{ \: volume =( l \times b \times h)}$

•for a right circular cylinder of base radius r and of height h ,

1)Curved Surface Area(L.S.A),

$\longrightarrow \sf\boxed{ L.S.A.=( 2\pi r h)}$

2)Total Surface Area(T.S.A.),

$\longrightarrow \sf\boxed{ T.S.A.=2\pi r (r+h)}$

3) Volume of,

$\longrightarrow \sf\boxed{ Volume=\pi r{}^{3}h}$

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$\huge\pink{\star}$

•for a Circle with with radius R,

1) Area is,

$\longrightarrow \sf\boxed{ Area=\pi \times R{}^{2}}$

2) Circumference is,

$\longrightarrow \sf\boxed{Circumference =2\times\pi \times R}$

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❏ Question:-

Q) The area of circle is 98.55 cm2 .find its circumference .

❏ Solution:-

❚➾ Given:- • Area=98.55 cm²

❚➾ To Find:- • Circumference=?

Let, the radius of the Circle is = R cm.

$\longrightarrow \sf Area=\pi \times R{}^{2}$

$\longrightarrow \sf 98.55=\frac{22}{7}\times R{}^{2}$

$\longrightarrow \sf 98.55\times\frac{7}{22}=R{}^{2}$

$\longrightarrow R=\sqrt{\frac{98.55\times7}{22}}$

$\longrightarrow R=5.599 \: cm$

$\longrightarrow\boxed {\red{ R=5.6 \: cm}\:\:(almost)}$

∴ Circumference of the circle is,

$\longrightarrow Circumference =2\times\frac{22}{\cancel7} \times \cancel{5.6}$

$\longrightarrow Circumference =2\times22\times 0.8$

$\longrightarrow\boxed {\red{Circumference =35.2 \:\:cm}}$

∴ Circumference of the Circle is =35.2 cm.

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$\underline{ \huge\mathfrak{hope \: this \: helps \: you}}$

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