Volumes and Surface Areas of Pyramids, Cones and Spheres

GeoGebra Institute of Hong Kong, Anthony OR 柯志明, Gentian, Feb 5, 2015

GeoGebraBook for elementary proofs of the formulas for volumes and surface areas of pyramids, cones and spheres.

Table of Contents

  1. Volume of Pyramids
    1. Trisecting the Cube into 3 Pyramids
    2. Volume of Pyramids
    3. Volume of Pyramids - Chinese Proof
  2. Curved Surface Area of Cones
    1. Curved Surface Area of Cones (Combined Version)
  3. Volume and Surface Area of Spheres
    1. Volume of Spheres
    2. Surface Area of Spheres

1.

Volume of Pyramids

  • 1. Trisecting the Cube into 3 Pyramids
  • 2. Volume of Pyramids
  • 3. Volume of Pyramids - Chinese Proof

1.1.

Trisecting the Cube into 3 Pyramids

Anthony Or. GeoGebra Institute of Hong Kong.
– Anthony OR 柯志明

1.2.

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1.3.

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2.

Curved Surface Area of Cones

  • 1. Curved Surface Area of Cones (Combined Version)

2.1.

Curved Surface Area of Cones (Combined Version)

– Anthony OR 柯志明

3.

Volume and Surface Area of Spheres

  • 1. Volume of Spheres
  • 2. Surface Area of Spheres

3.1.

Volume of Spheres

The figure shows a hemisphere of radius [i]r[/i] and a cylinder of base radius and height [i]r[/i] with an inverted cone of the same height and base radius removed. Drag the red point to see the cross-sections of the two solids at a height [i]h[/i].[br](a) Express [i]x[/i] and [i]y[/i] in terms of [i]r[/i] and [i]h[/i].[br](b) Are the cross-sections equal in area?[br](c) Hence show that the volume of the sphere of radius [i]r[/i] is 4/3 π [i]r[/i]³.
– Anthony OR 柯志明

3.2.

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