Question

Keliling alas kerucut 44 cm. jika panjang garis pelukis 25 cm. hitung volume kerucut dan luas kerucut ?

Answer 1

Kel alas = π.d
     44      = 22/7 .d
44 :22/7 = d
44 x 7/22 = d
14 = d atau r = 7
tinggi kerucut = 24 ( karena Phytagoras 7,24,25)
V.kerucut = 1/3 L.alas x tinggi
= 1/3 π.r²x t
=1/3 22/7.7.7 x 24
=22 . 7 = 154 cm³

Answer 2

- alas kerucut = lingkaran
- K. Lingkaran = 44
  2 . phi . r = 44
  phi . r = 22
  22/7 . r = 22
  r = 22.7/22
  r = 7 cm
- r = 7 cm, s = 25 cm, maka : 
  t kerucut = (akar) 25 kuadrat - 7 kuadrat
  t kerucut = (akar) 25.25 - 7.7
  t kerucut = (akar) 625 - 49
  t kerucut = (akar) 576
  t kerucut = 24 cm

- V = 1/3. phi. r kuadrat . t
  V = 1/3 . 22/7 . 7 . 7 . 24
  V = 924 cm kubik

- L = phi. r ( r + s )
  L = 22/7 . 7 ( 7+25 )
  L = 22 (32)
  L = 704 cm persegi