"Question 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 the figure). If the label is placed 2 cm from top and bottom, what is the area of the label.
Class 8 Mensuration Page 186"
Answers
Mensuration:
Mensuration is the branch of mathematics which concerns itself with the measurement of Lengths, areas & volume of different geometrical shapes or figures.
Surface area:
The surface area of a solid is the sum of the areas of the plane or curved faces of the solid.
It is measured in square units such as square centimetre (cm²) and square metre (m²).
Whenever we talk about a total surface area of a cylinder the cylinder must be closed at both the ends by two circular regions or it should be a cylindrical solid object.
Total surface area of a solid cylinder= curved surface area + sum of the areas of two circular ends of the cylinder
= 2πrh+ 2πr²
Total surface area of a solid cylinder= 2πr(h+r)
The lateral surface area of the curved surface area of a cylinder= 2πrh
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Solution:
Given:
Diameter of cylindrical container(d) = 14 cm
Radius of cylindrical container (r) = 7 cm
Height of cylindrical container (h)= 20 cm
Height of the label (h) = 20 –(2 +2)= 20 – 4= 16
h= 16 cm
Curved surface area of label = 2πrh
= 2 × 22/7× 7× 16
= 44× 16
= 704 cm²
Hence, the area of the label = 704 cm²
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Hope this will help you...
