Nilai Sigma 21 n=2 (5n – 6) = …

by

Jawab:

21
 Σ   (5n – 6) = 4 + 9 + 14 + … + 99
n=2                              n=20
S₂₀ = 20÷2 (4 + 99)
      = 10 (103)
      = 1030
  Diketahui prisma segitiga tegak ABC.DEF. panjang AB = 4 cm, BC = 6 cm, AC = 2√7, dan CF = 8 cm.