Lessons

1. Basics
2. Deductive Reasoning
3 - Parallel lines
4 - Congruent Triangles
6 - Inequalities
7 - Similar Polygon
8 - Rt. Triangles
9 - Circles
10 - Constructions
11 - Areas of 2D objects
12 - Areas and Volumes
13 - Coordinates
14 - Reflection/Rotation

Pyramids

Objective:

• Learning and using the parts of pyramids, finding areas and volumes of pyramids

Lesson 12-2 Pyramids:

Pyramid: Structure with a base and triangular sides meeting at a point

Vertex: The point where the triangular sides meet

Base: The bottom of the structure

Altitude: The segment from the vertex perpendicular to the base. It is also the height of the pyramid.

Lateral faces: The triangular faces

Lateral edges: The segment where the lateral faces intersects.

Regular pyramids: These pyramids have the following properties: (1) The base is a regular polygon  (2)All lateral faces are congruent isosceles triangles. (3) The altitude meets the base at its center, O.

Slant Height (l): The height of a lateral face

 Theorem 12-3 The Lateral area of a regular pyramid equals half the perimeter of the base times the slant height (L.A.=1/2pl) The slant height: 10 The perimeter of the polygon: 60 Lateral area= 1/2 (60)(10) =300 Theorem 12-4 The Volume of a pyramid equal one third the area of the base the height of the pyramid. (V=1/3 Bh) The height: 10 The area of the polygon: 25 Volume= 1/3 (25)(10) = 250/3

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