Question

plzz help me....
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Answer 1

$\large{\red{\bold{\underline{Given:}}}}$

$\sf \: Radius \: of \: the \: cylinder = 28cm \\ \\ \sf \: Height \: of \: cylinder = 42cm$

$\large{\green{\bold{\underline{To \: Find:}}}}$

$\sf \: (i) \: Total \: surface \: area \: of \: cylinder \\ \\ \sf \: (ii) \: Curved \: surface \: area \: of \: cylinder$

$\large{\blue{\bold{\underline{Formula \: Used:}}}}$

$\sf \: Total \: surface \: area = 2\pi r(r + h) \\ \\ \sf \: Curved \: surface \: area = 2\pi rh$

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

$\sf \: Let \: the \: radius \: of \: the \: cylinder \: be \: r, \\ \sf \: and \: the \: height \: of \: the \: cylinder \: as \: h$

$\large{\green{\bold{\underline{Then:}}}}$

$\sf \: (i) \: Total \: surface \: area = 2\pi r(r + h) \\ \\ \rightarrow \: \sf Total \: surface \: area = 2 \times \frac{22}{7} \times 28(28 + 42) \\ \\ \rightarrow \: \sf Total \: surface \: area = 2 \times \frac{22}{7} \times 28(70) \\ \\ \rightarrow \: \sf \: Total \: surface \: area = \frac{44}{\cancel7} \times \cancel28 \times 70 \\ \\ \rightarrow \: \sf \: Total \: surface \: area = 44 \times 4 \times 70 \\ \\ \rightarrow \: \sf \: Total \: surface \: area = 12320 \: {cm}^{2}$

$\large{\pink{\bold{\underline{Now:}}}}$

$\sf \: (ii) \: Curved \: surface \: area = 2\pi rh \\ \\ \rightarrow \: \sf \: Curved \: surface \: area = 2 \times \frac{22}{7} \times 28 \times 42 \\ \\ \rightarrow \: \sf \: Curved \: surface \: area = 2 \times \frac{22}{\cancel7} \times \cancel28 \times 42 \\ \\ \rightarrow \: \sf \: Curved \: surface \: area = 44 \times 4 \times 42 \\ \\ \rightarrow \: \sf \: Curved \: surface \: area = 7392 \: {cm}^{2}$

$\large{\orange{\bold{\underline{Therefore:}}}}$

$\sf \: The \: total \: surface \: area \: of \: cylinder \: is \\ \sf \: 12320 {cm}^{2} \: and \: curved \: surface \: area \: is \: 7392 {cm}^{2}.$

Answer 2

Answer:

solution

$\sf \: Let \: the \: radius \: of \: the \: cylinder \: be \: r, \\ \sf \: and \: the \: height \: of \: the \: cylinder \: as \: h$

$\large{\orange{\bold{\underline{Then:}}}}$

$\sf \: (i) \: Total \: surface \: area = 2\pi r(r + h) \\ \\ \rightarrow \: \sf Total \: surface \: area = 2 \times \frac{22}{7} \times 28(28 + 42) \\ \\ \rightarrow \: \sf Total \: surface \: area = 2 \times \frac{22}{7} \times 28(70) \\ \\ \rightarrow \: \sf \: Total \: surface \: area = \frac{44}{\cancel7} \times \cancel28 \times 70 \\ \\ \rightarrow \: \sf \: Total \: surface \: area = 44 \times 4 \times 70 \\ \\ \rightarrow \: \sf \: Total \: surface \: area = 12320 \: {cm}^{2}$

$\large{\pink{\bold{\underline{Now:}}}}$

$\sf \: (ii) \: Curved \: surface \: area = 2\pi rh \\ \\ \rightarrow \: \sf \: Curved \: surface \: area = 2 \times \frac{22}{7} \times 28 \times 42 \\ \\ \rightarrow \: \sf \: Curved \: surface \: area = 2 \times \frac{22}{\cancel7} \times \cancel28 \times 42 \\ \\ \rightarrow \: \sf \: Curved \: surface \: area = 44 \times 4 \times 42 \\ \\ \rightarrow \: \sf \: Curved \: surface \: area = 7392 \: {cm}^{2}$

$\large{\blue{\bold{\underline{Therefore:}}}}$

$\sf \: The \: total \: surface \: area \: of \: cylinder \: is \\ \sf \: 12320 {cm}^{2} \: and \: curved \: surface \: area \: is \: 7392 {cm}^{2}.$