The cost of painting the total surface area of a cone at 25 paise per

1.	The cost of painting the total surface area of a cone at 25 paise per cm? is176. Find thevolume of the cone, if its slant height is 25 cm.
Answer» Painting cost = 25paise/cm² = 0.25rupee/cm² πr(l+r) = 176/0.25 =704cm²πr(25+r) =70425r +r² = 704/π =224.1 r²+25r-224.1 = 0 r = (-25±√(25²+4×224.1))/2r = -32 , 7 so, r =7cmh = √(25²-7²) = 24cm so, volume = πr²h/3 =1231.5 cm³

The cost of painting the total surface area of a cone at 25 paise per cm? is176. Find thevolume of the cone, if its slant height is 25 cm.

Answer»

Painting cost = 25paise/cm² = 0.25rupee/cm²

πr(l+r) = 176/0.25 =704cm²πr(25+r) =70425r +r²

= 704/π =224.1

r²+25r-224.1 = 0

r = (-25±√(25²+4×224.1))/2r = -32 , 7

so, r =7cmh = √(25²-7²) = 24cm

so, volume = πr²h/3 =1231.5 cm³