9-5 Three-Dimensional Figures

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9-5 Three-Dimensional Figures

2. The radius of a circle is 9 cm. What is its circumference?

1. The diameter of a circle is 12 in. What is the circumference?

Warm UpSolve. Use 3.14 for .

37.68 in.

56.52 cm

452.16 ft2

3. Find the area of a circle with a 12 ftradius.

9-5 Three-Dimensional Figures

Problem of the Day

To measure the perimeter of her square patio, Becky used an old bicycle wheel with a 22 in. diameter. She rolled the wheel from one corner of the patio along the edge to the next. The wheel made 6.75 revolutions. What is the perimeter in feet of the patio? Use 3.14 for . 155.43 ft

9-5 Three-Dimensional Figures

Review of MA.5.G.3.1 Analyze and compare the properties…of three-dimensional solids (polyhedra)…

Also Prep for MA.6.G.4.3

Sunshine State Standards

9-5 Three-Dimensional Figures

Vocabulary

polyhedron cylinderface pyramidedge conevertex sphereprismbase

9-5 Three-Dimensional Figures

A polyhedron is a three-dimensional object with flat surfaces, called faces, that are polygons.

When two faces of a three-dimensional figure share a side, they form an edge. A point at which three or more edges meet is a vertex (plural: vertices).

9-5 Three-Dimensional Figures

A prism is a polyhedron with two congruent, parallel bases, and other faces that are all parallelograms. A prism is named for the shape of its bases. A cylinder also has two congruent, parallel bases, but bases of a cylinder are circular. A cylinder is not a polyhedron because not every surface is a polygon.

9-5 Three-Dimensional Figures

A pyramid has one polygon-shaped base and three or more triangular faces that share a vertex. A pyramid is named for the shape of its base. A cone has a circular base and a curved surface that comes to a point. A sphere has no base and one curved surface. All points on the surface are the same distance from a point called the center of the sphere.

9-5 Three-Dimensional Figures

Cones and spheres are not polyhedrons because they have curved surfaces.

Helpful Hint

9-5 Three-Dimensional Figures

Check It Out: Example 2B

Name the three-dimensional figure represented by the object.

The figure is a polyhedron.

All the faces are flat and are polygons.

The figure is a rectangular prism.

There are two congruent, parallel bases, so the figure is a prism. The bases are rectangles.