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Q.1. What is the curved surface area of a cylinder obtained from a square of side 5 cm?
25 cm^{2}
Q.2. Radius ofthebaseofa paper cylinder is 7 cm and it is cut along its height. Find the length of the paper obtained.
l= circumference of base = 2πr = 2 x 22/7 x 7 = 44 cm
Q.3. Find the height of a right circular cylinder made from a rectangle of length 15 cm and breadth 12 cm. It is curved along its length.
12 cm
Q.4. What is an example of right circular cylinder?
Gas cylinders, cans, pipes, etc., are reallife examples of a right circular cylinder.
Q.5. What do you mean by right circular cylinder?
A right circular cylinder is a cylinder whose bases are circular in shape and parallel to each other. Both the bases are connected to each other through a lateral or curved surface.
Q.6. Find the volume of a right cylinder, if the radius and height of the cylinder are 20 cm and 30 cm respectively.
Volume of a right cylinder = πr^{2}h cubic units
Given, r = 20 cm h = 30 cm
Therefore, using the formula, we get;
Volume = 3.14 × 20^{2} × 30
= 3.14 × 20 × 20 × 30
= 37680
Hence, the volume of the given right cylinder is 37680 cm^{3}.
Q.7. What is the formula of area of the cylinder?
The formula of area of a cylinder is
A = 2πr (h + r) sq.unit
Where r is the radius of and h is the height of the cylinder.
Q.8. What is the total surface area of the cylinder?
The total surface area of the cylinder is equal to the sum of curved surface area and areas of circular bases.
Q.9. Calculate the cost required to paint a container which is in the shape of a right circular cylinder having a base radius of 7 m and height 13 m. If the painting cost of the container is INR 2.5/m^{2}. (Take π = 22/7)
Total surface area of aquarium = 2πr (h + r)= 2 x 22/7 x 7 x 20 = 880 m^{2}
Total cost of painting the container = 2.5 × 880 = Rs. 2200
Q.10. Find the total surface area of a container in cylindrical shape whose diameter is 28 cm and height is 15 cm.
Given, diameter = 28 cm, so radius = 28/2 = 14 cm
and height = 15 cm
By the formula of total surface are, we know;
TSA = 2πr (h + r) = 2x 22/7 x 14 x (15 + 14)
TSA = 2 x 22 x 2 x 29
TSA = 2552 sq.cm
Hence, the total surface area of container is 2552 sq.cm.
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