Q4 of 32 Page 119

What will be the cost of making a closed cone of tin sheet having radius of base 6 m and slant height 8 m if the rate of making is Rs.10 per sq.m?

Given: radius of base of cone (r) = 6 m

Slant height of cone (l) = 8 m


Since, this is a closed cone made of tin sheet. We need to find total surface area of the cone, it given by


TSA = πrl + πr2


⇒ TSA = πr (l + r)


Substituting values in the formula, we get



⇒


According to the question,


Cost of 1 m2 = Rs. 10


Cost of 264 m2 = 10 × 264


= Rs. 2640


Thus, cost of making the required cone is Rs. 2640.


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