RD Sharma - Mathematics

Book: RD Sharma - Mathematics

Chapter: 20. Surface Area and Volume of a Right Circular Cone

Subject: Mathematics - Class 9th

Q. No. 18 of Exercise 20.1

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18

A tent is in the form of a right circular cylinder surmounted by a cone. The diameter of cylinder is 24 m. The height of the cylindrical portion is 11 m while the vertex of the cone is 16 m above the ground. Find the area of the canvas required for the tent.

For cylindrical part, we have


Diameter = 24 m so, radius r = 24/2 = 12 m ,


Height = h = 11 m


For conical part, we have


Height of the cone = (16-11) m = 5 m


Slant height = m = 13 m


Hence, Area of the canvas required


= Curved surface area of cone + Curved surface area of cylinder


= πrl+2πrh=πr(l+2h) = ×12×(13+22) m2 = 1320 m2


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