Question

Sebuah kerucut yg panjang garis pelukisnya 25 cm, diketahui luas selimutny 550 cm². volume kerucut tersebut adalah...

Answer 1

Luas selimut = π * r * garis pelukis
550 = 3,14 * r * 25
550 = 78,5 r
r = 550/78,5
r = 7 cm

s² = t² + r²
25² = t² + 7²
625 = t² + 49
t² = 625 - 49
t² = 579
t = √579
t = 24 cm

Volume = 1/3 π r² t
Volume = 1/3 * 22/7 * 7² * 24
Volume = 1232 cm²

Answer 2

L slimut = pi x r x s
550  = 22/7 x r x 25
22 = 22/7 x r
r = 22 x 7/22
r = 7 cm

t^2 = s^2 - r^2
     = 25^2 - 7^2
      = 625 - 49
      =√576
   t = 24 cm

V = 1/3 X pi r^2 x t
   = 1/3 x 22/7 x 7^2 x24
   = 22 x 7 x 8
  =1.232 cm³