Question
A tent is in the shape of a cylinder surmounted by a conical top. If the height and diameter of the cylindrical part are 2.1 m and 4 m respectively, and the slant height of the top is 2.8 m, find the area of the canvas used for making the tent. Also, find the cost of the canvas of the tent at the rate of Rs 500 per m2. (Note that the base of the tent will not be covered with canvas.)
Solution
Let r m be the radius and l m be the slant height of the cone, then
r = 2 m, and l = 2.8 m
Let r1 m be the radius and h m be the height of the cylinder, then
Now, r1 – 2 m and h = 2.1 m
Area of the canvas used
= CSA of cone + CSA of cylinder
= πrl + 2 πr1h
= πrl + 2πrh [r = r1]
= π r (l + 2h) m2 
and Cost of canvas of the tent
= Rs. (500 x 44)
= Rs. 22,000.
