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9 votes
9 votes
(Hurry) guys pls help me, i don’t understand what my teacher taught me

(Hurry) guys pls help me, i don’t understand what my teacher taught me-example-1
User P S M
by
2.8k points

2 Answers

26 votes
26 votes

Answer:

Explanation:

me too i dont know

User AdamOutler
by
2.9k points
20 votes
20 votes

Answer:

  • 8 cm
  • ≈ 117.6 cm³

Explanation:

Total surface area:

  • A = 4(1/2*7*l) + 7² = 14l + 49, where l is a slant height

We are given:

  • A = 161 cm²

Find the value of l:

  • 14l + 49 = 161
  • 14l = 112
  • l = 112/14
  • l = 8 cm

Use Pythagorean to find the height h of the pyramid:

  • l² = h² + (7/2)²
  • 8² = h² + 3.5²
  • h² = 8² - 3.5²
  • h² = 51.75
  • h = √51.75
  • h ≈ 7.2 cm

Find the volume:

  • V = 1/3Bh
  • V = 1/3*7²*7.2
  • V = 117.6 cm³
User Humberto Pinheiro
by
3.5k points