Question

Question:

Eighty equal circular discs, each 6 mm thick and radius 7 cm are placed one above the other to form a cylinder, find the total surface area of the cylinder.

◇Solve these question with full explanation and in detail.​

Answer 1

Answer:

≈ 2418 cm²

Step-by-step explanation:

Height

= (80)(0.6)

= 48 cm

radius = 7 cm

total surface area of cylinder =

$2\pi \: r \: (h + r)$

= (2) ( 3.14) (7) (48+7)

= 43.96 ( 55)

= 2417.8 cm²

Answer 2

$\large\underline{\sf{Solution-}}$

Given that,

Eighty equal circular discs, each 6 mm thick and radius 7 cm are placed one above the other to form a cylinder.

Since, 80 equal circular discs, each 6 mm thick are placed one above the other to form a cylinder.

So, height of cylinder, h = 6 × 80 = 480 mm = 48 cm.

[ We know, 1cm = 10 mm ]

Radius of cylinder, r = 7 cm

We know,

Total Surface Area of cylinder of height h and radius r is given by

${{\rm :\longmapsto\:\boxed{{\sf\green{Surface Area_{(Cylinder)}\: = \:2\pi r(h +r)}}}}}$

So, on substituting the values, we get

$\rm :\longmapsto\:Surface \: Area_{Cylinder} = 2 \times \dfrac{22}{7} \times 7 \times (48 + 7)$

$\rm :\longmapsto\:Surface \: Area_{Cylinder} = 2 \times 22 \times 55$

$\rm\implies \:\boxed{\tt{ \: Surface Area_{Cylinder} = 2420 \: {cm}^{2} \: }}$

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ADDITIONAL INFORMATION

Volume of cylinder = πr²h

T.S.A of cylinder = 2πrh + 2πr²

Volume of cone = ⅓ πr²h

C.S.A of cone = πrl

T.S.A of cone = πrl + πr²

Volume of cuboid = l × b × h

C.S.A of cuboid = 2(l + b)h

T.S.A of cuboid = 2(lb + bh + lh)

C.S.A of cube = 4a²

T.S.A of cube = 6a²

Volume of cube = a³

Volume of sphere = 4/3πr³

Surface area of sphere = 4πr²

Volume of hemisphere = ⅔ πr³

C.S.A of hemisphere = 2πr²

T.S.A of hemisphere = 3πr²