Question

The cost of painting the total surface area of a cone at 25 paise per cm² is Rs.176. Find the volume of the cone, if its slant height is 25 cm.

Answer 1

25 pasie = rs1/4
1/4rs = 1m^2
1rs = 4m^2
176 rs = 704 cm^2
Total surface area of cone = πr (r+l)
πr^2+πl = 704
3.14×r^2+3.14×25 = 704
3.14r^2+78.5 = 704
3.14= 704-78.5
3.14r^2 = 625.5
πr^2 = 625.5

Answer 2

hai here is Ur ans my dear:-

=>given l= 25cm

=>total surface area of cone = 176/25×100

=>πr(r+l)=704

=>22/7×r(r+25)=704

=>r(r+25)=704×7/22

=>r^2+25r=224

=>r^2+25r-224=0

=>r+32r-7r-224=0

=>r(r+32)-7(r+32)=0

=>(r-7)(r+32)=0

=>r-7=0. <=>. r+32=0

=>r=7. <=>. r=-32

=>therefore,r=7cm (negative values shouldn't been taken)

=>therefore ,l^2=h^2+r^2

=>25^2=h^2+7^2

=>625=h^2+49

=>625-49=h^2

=>√576=4

=>h=24cm

=>volume of a cone =1/3 πr^2h

=>1/3×22/7×7×7×24

=> 154×8

=>>1232cm^3

if my ans is useful n mark as brainlist