along a. highway 50 conical pillars are constructed each pillars has a diameter of 28 cm and vertical height 18 cm . find the cost of painting these pillars at the rate of Rs 120 sqaure m
Answers
Given :- Along a highway 50conical pillars are constructed. Each pillar has base diameter 28 cm and vertical height 18cm. find the total cost of painting these pillars at the rate of Rs. 120 per m².
Solution :-
we know that,
Slant height of cone = √[radius² + height²]
CSA of cone = π * radius * slant height .
Radius = diameter / 2 .
So,
→ Radius of cone = 28/2 = 14 cm.
then,
→ slant height of cone = √[14² + 18²] = √[196 + 324] = √(520) = 2√130 cm.
therefore,
→ curved surface area of one conical pillar = (22/7) * 14 * (2√130) = 22 * 2 * 2√130 = 88√130 cm².
hence,
→ curved surface area of 50 conical pillar = 50 * 88 * 11.40 = 50160 cm².
now, we know that,
10000 cm² = 1m².
then,
→ 10000 cm² = 1m².
→ 1 cm² = (1/10000) m²
→ 50160 cm² = (1/10000) * 50160 = 5.016 m²
hence,
→ total cost of painting these pillars at the rate of Rs. 120 per m² = 120 * 5.016 = Rs.601.92 (Ans.)
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