A regular octagonal pyramid. Each side of the base is 6 cm long. it has a height of 10cm. Find the surface area of the pyramid

9514 1404 393

  470.16 cm²

Step-by-step explanation:

The apothem of the base is used for two purposes: to find the area of the base, and to find the slant height of each face.

The apothem of the base for side length s is ...

  s/2 = a·tan(π/8)

  a = s/(2·tan(π/8)) ≈ 7.24 cm

The slant height of a triangular face is found using the Pythagorean theorem. The apothem of the base and the height are legs of the right triangle whose hypotenuse is the slant height. For slant height x, we have ...

  x² = 10² + a² = 100 +52.46

  x ≈ √152.46 ≈ 12.35

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The area of the 8 triangular faces will be ...

  A = 1/2Px . . . . where P is the perimeter of the pyramid

The area of the base will be ...

  A = 1/2Pa

So, the total surface area is ...

  A = 1/2P(a + x) = (1/2)(8)(6 cm)(7.24 +12.35 cm) ≈ 470.16 cm²

45

step-by-step explanation:

to find a percentage, add a decimal in front and multiply it by the other number.

.25 times 180= 45