Question

find curved and total surface area of a cylinder when r=7cm,h=12cm​

Answer 1

S O L U T I O N :

Given :

• Radius, (r) = 7 cm
• Height, (h) = 12 cm

Explanation :

As we know that formula of curved surface area of cylinder & total surface area of cylinder :

• C.S.A of cylinder = 2πrh
• T.S.A. of cylinder = πr²h + 2πrh

According to the question :

➝ C.S.A of cylinder = 2πrh

➝ C.S.A of cylinder = 2 × 22/7 × 7 × 12

➝ C.S.A of cylinder = 44/7 × 7 × 12

➝ C.S.A of cylinder = (44 × 12)cm²

➝ C.S.A of cylinder = 528 cm²

&

➝ T.S.A of cylinder = πr²h + 2πrh

➝ T.S.A of cylinder = πrh(r + 2)

➝ T.S.A of cylinder = 22/7 × 7 × 12( 7 + 2)

➝ T.S.A of cylinder = 22 × 12(9)

➝ T.S.A of cylinder = 22 × 108

➝ T.S.A of cylinder = 2376 cm²

Answer 2

Answer:

Given :-

• Radius of cylinder (R) = 7 cm
• Height of cylinder (H) = 12 cm

To Find :-

• Curved surface area
• Total surface area

Solution :-

As we know CSA of cylinder is 2πrh

$\sf \implies \: CSA = 2 \times \dfrac{22}{7} \times 7 \times 12$

$\sf \implies CSA = 2 \times 22 \times 1 \times 12$

$\sf \implies \: CSA = 44 \times 12$

$\sf \implies \: CSA = 526 \: cm {}^{2}$

Now,

Let's find TSA of cylinder

TSA of cylinder = πrh (r + 2)

$\sf \implies TSA \: = \dfrac{22}{7} \times 7 \times 12(7 + 2)$

$\sf \implies \: TSA = \dfrac{22}{7} \times 7 \times 12 \times 9$

$\sf \implies \: TSA = 22 \times 12 \times 9$

$\sf \implies \: TSA = 2376 cm^{2}$