Question

ncert class 8 maths chapter 11. exercise 11.3. question no 10

Answer 1

10. A company packages its milk powder in cylindrical container whose base has a diameter of 14 cm and height 20 cm. Company places a label around the surface of the container (as shown in figure). If the label is placed 2 cm from top and bottom, what is the area of the label ?

$\huge{\mathcal{Solution :}}$

Diameter of cylindrical container = 14 cm.

Radius = diameter / 2 = 7 cm.

Height = 20 cm.

Now,

Height of the label = 20 - 2 - 2 = 16 cm.

CSA of label = 2 π rh

$2 \times \frac{22}{ \cancel7} \times \cancel7 \times 16 \\ \\ 2 \times 22 \times 16 \\ \\ 44 \times 16 \\ \\ = 704 \: cm {}^{2}$

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Answer 2

hight of the lebal =20-2-2=16cm. radius of the label=
$14 \div 2$
=7cm. label is in the form of a cylinder heaving it's radiusand height as 7cm and 16cm. Area of the label=
$2\pi rh$
=
$2 \times 22 \div 7 \times 7cm \times 16cm$
=704cm2 I hope it helps you