Question

Find the surface area of a sphere having radius 7 cm
1 616 sq.cm.
2 519 sq.cm
3 890 sq.cm​

Answer 1

Given

• Radius of sphere = 7cm

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To find

• Surface area of the sphere.

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Solution

• We have a sphere with radius of 7cm. Here, surface area of the sphere has been used.

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☆ TSA = 4πr²

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→ TSA = 4 × 22/7 × 7 × 7

→ TSA = 4 × 22 × 7

→ TSA = 28 × 22

→ TSA = 616cm²

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Hence,

• Surface area of the given sphere is 616cm².

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⇛ Formulas related to Volume and Surface area

$\begin{array}{|c|c|c|}\cline{1-3}\bf Shape&\bf Volume\ formula&\bf Surface\ area formula\\\cline{1-3}\sf Cube&\tt l^3}&\tt 6l^2\\\cline{1-3}\sf Cuboid&\tt lbh&\tt 2(lb+bh+lh)\\\cline{1-3}\sf Cylinder&\tt {\pi}r^2h&\tt 2\pi{r}(r+h)\\\cline{1-3}\sf Hollow\ cylinder&\tt \pi{h}(R^2-r^2)&\tt 2\pi{rh}+2\pi{Rh}+2\pi(R^2-r^2)\\\cline{1-3}\sf Cone&\tt 1/3\ \pi{r^2}h&\tt \pi{r}(r+s)\\\cline{1-3}\sf Sphere&\tt 4/3\ \pi{r}^3&\tt 4\pi{r}^2\\\cline{1-3}\sf Hemisphere&\tt 2/3\ \pi{r^3}&\tt 3\pi{r}^2\\\cline{1-3}\end{array}$

Answer 2

$\begin{gathered}\bf{\underline{\underline{Given :-}}}\\\end{gathered}$⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀

★ $\sf{Radius \ = \ 7cm}$.

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$\begin{gathered}\bf{\underline{\underline{To\:find : - }}}\\\end{gathered}$

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★ $\sf{Surface \ area}$.

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• $\sf{We \ know \ that}$ ,

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$\large{\boxed{\boxed{\bf{ SA \ of \ sphere = \ 4πr² }}}}$

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$\tt{SA \ = 4 \ x \ 22 / 7 \ x 7² }$

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$\tt{SA \ = \ 616cm² }$

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★ $\begin{gathered}\bf{\underline{\underline{So, \ Option \ 1] \ 616cm² \ is \ correct }}}\\\end{gathered}$