Question

The diameter of the base of a right circular cylinder is 28 cm and its height is 21 cm. find
its (i) curved surface area (ii) total surface area and (iii) volume
​

Answer 1

$\large{\underline{\underline{\bold{\red{\sf{Question}}}}}}$

The diameter of the base of a right circular cylinder is 28 cm and its height is 21 cm. find

its (i) curved surface area (ii) total surface area and (iii) volume.

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$\large{\underline{\underline{\bold{\red{\sf{Solution}}}}}}$

Diameter = 28cm.

As we know that radius is half of diameter:.

Radius=$\frac{28}{2}$

$R=\cancel\frac{28}{2}⇒14cm$

(i)

$C.S.A \:of\: Cylinder = 2 π rh$

$Putting\: values$

$2\times\frac{22}{7}\times{14}\times{21}$

$\cancel\frac{7}{21}⇒3$

⇒2 × 22 × 14 × 3

$\large{\underline{\underline{\bold{\blue{\sf{Answer=1848}}}}}}$

(ii)

$T.S.A \:of \:Cylinder⇒[tex]2πr(h + r)$

$Putting \:Values$

$2\times\frac{22}{7}\times{14}(21 + 14)$

$\cancel\frac{7}{14}⇒3$

$2×22×2(35)$

$88×35$

$\large{\underline{\underline{\bold{\orange{\sf{Answer:.3080cm}}}}}}$

(iii)

Volume of Cylinder=π r²h

$Putting \:Values$

$\frac{22}{7}\times{14}\times{14}\times{21}$

$\cancel\frac{7}{21} ⇒3$

22×14×14×3

$\large{\underline{\underline{\bold{\green{\sf{Answer:.4304}}}}}}$

Answer 2

$\huge \color{red} \boxed{\colorbox{pink}{Solution}}$

➻ Diameter of the base of a right circular cylinder is 28 cm.

➻ Radius of the base of a right circular cylinder (r) is 14 cm.

➻ Height of a right circular cylinder is 21 cm.

1 ) Curved surface area of a right circular cylinder

$\tt = 2 \pi rh \: = 2 \times \frac{22}{7} \times 14 \times 21 \\ \tt = 1848 \: {cm}^{2}$

Hence the answer is 1848 cm²..

2 ) Total surface area of a right circular cylinder

$\tt = 2 \pi r(r + h) \\ \tt = 2 \times \frac{22}{7} \times 14(14 + 21) \\ \tt = 2 \times \frac{22}{7} \times 14 \times 35 \\ \tt = 3080 \: {cm}^{2}$

3 ) Volume of a right circular cylinder

$\tt \pi {r}^{2}h = \frac{22}{7} \times 14 \times 14 \times 21 = 12936 {cm}^{3}$

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