Question

2 The lateral surface area and the total surface area of a cylinder with base radius 7 m and height 9 m are respectively 1 a) 396 m² 704 m b) 704 m2, 396 m c) 396 m, 704 m d) 704 m, 396 m​

Answer 1

Step-by-step explanation:

Radius of cylinder, r=7 m.

And the height of the cylinder, h=9 m.

For finding the lateral surface area we apply the formula of lateral surface area i.e. 2πrh

Lateral surface area = Area of the curved surface=2πrh

=2×22/7×7m×9m

=396m^2.

And,

for finding the total surface area we have to find the area of two circular surfaces and add with the lateral surface area.

We know that the area of the circle is πr2.

∴Area of two circular curved surfaces=2×πr2=2×227×7m×7m

=308m2.

Now,

The total surface area is the sum of lateral surface area and the two circular surfaces area,i.e,

396m^2+308m^2=704m^2

Hence, option A is the correct answer.

Note: Whenever we face such a type of question the key concept for solving the question is calculate the area by simply applying the formula of lateral surface area and for total surface area we have to add the circular surface area to the curved surface area. We can figure it out by making a diagram of the cylinder to know about lateral surface and circular surface area.

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