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Chapter 11 Section 11.1 – Space Figures and Cross Sections. Objectives: To recognize polyhedra and their parts To visualize cross sections of space figures. Polyhedron a three-dimensional figure whose surfaces are polygons Face name for a side of a polyhedron
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Chapter 11Section 11.1 – Space Figures and Cross Sections Objectives: To recognize polyhedra and their parts To visualize cross sections of space figures
Polyhedron a three-dimensional figure whose surfaces are polygons • Face name for a side of a polyhedron • Edge a segment that is formed by the intersection of two faces • Vertex a point where three or more edges intersect
Faces Vertex Edge
A • Ex: • Identify the vertices/edges/faces of the figure D B C E H F G
Euler’s Formula • The numbers of faces (F), vertices (V), and edges (E) of a polyhedron are related by the formula: F + V = E + 2
Ex: Using Euler’s Formula • Use Euler’s Formula to find the number of edges on a polyhedron with eight triangular faces.
Cross-Section the intersection of a solid and a plane. You can think of it as a very thin slice of the solid. • Examples of Cross Sections • One slice of bread in a loaf • CAT Scans and MRI’s
Homework #25 • Due Tuesday (April 09) • Page 601 • # 1 – 19 all
Section 11.2 – Surface Areas of Prisms and Cylinders • Objectives: To find the surface area of a prism To find the surface area of a cylinder
Prism a polyhedron with exactly two congruent, parallel faces called bases. The other faces of the prism are called lateral faces. • Altitude of a prism is a perpendicular segment that joins the planes of the bases. • Height of the prism is the length of an altitude.
Lateral Area of a prism is the sum of the areas of the lateral faces. • Surface Area the sum of the lateral area of the area of the two bases.
Theorem 11.1 – Lateral and Surface Areas of a Prism • The lateral area of a right prism is the product of the perimeter of the base and the height. L.A. = p · h • The surface area of a right prism is the sum of the lateral area and the areas of the two bases. S.A. = L.A. + 2B
Cylinder has two congruent parallel bases, just like a prism. However, the bases of a cylinder are circles. • Altitude of a cylinder is a perpendicular segment that joins the planes of the bases • Height of a cylinder is the length of an altitude
Lateral Area visualize “unrolling” the curved surface of the cylinder. Imagine taking the label off of a water bottle. The area of the resulting rectangle is the lateral area. • Surface Area of a cylinder is the sum of the lateral area and the areas of the two circular bases.
Theorem 11.2 – Lateral and Surface Areas of a Cylinder • The lateral area of a right cylinder is the product of the circumference of the base and the height of the cylinder. L.A. = 2Πrh-or- L.A. =Πdh • The surface area of a right cylinder is the sum of the lateral area and the areas of the two bases. S.A. = L.A. + 2B -or- S.A. = 2Πrh + 2Π
Homework # 26 • Due Wednesday (April 10) • Page 611 – 612 • #1 – 19 all
Section 11.3 – Surface Areas of Pyramids and Cones • Objectives: To find the surface area of a pyramid To find the surface area of a cone
Pyramid a polyhedron in which one face (the base) can be any polygon and the other faces (lateral faces) are triangles that meet at a common vertex (vertex of the pyramid). • Altitude of a pyramid is the perpendicular segment from the vertex to the plane of the base. • Height length of the altitude
Regular Pyramid a pyramid whose base is a regular polygon and whose lateral faces are congruent isosceles triangles. • Slant height (l) the length of the altitude of a lateral face of the pyramid.
Lateral Area of a pyramid is the sum of the areas of the congruent lateral faces. • Surface Area of a pyramid is the sum of the lateral area and the area of its base
Theorem 11.3 – Lateral and Surface Areas of a Regular Pyramid • The lateral area of a regular pyramid is half the product of the perimeter of the base and the slant height. L.A. = p · l • The surface area of a regular pyramid is the sum of the lateral area and the area of the base. S.A. = L.A. + B
Cone has a pointed top like a pyramid, but its base is a circle • Altitude a perpendicular segment from the vertex of the cone to the center of its base • Height the length of the altitude • Slant Height the distance from the vertex to a point on the edge of the base
Lateral Area as with a pyramid, it is the circumference of the base times the slant height. • Surface Area similar to a pyramid as well, it is the sum of the lateral area and the area of the base.
Theorem 11.4 – Lateral and Surface Areas of a Cone • The lateral area of a right cone is half the product of the circumference of the base and the slant height. L.A. = · 2Πr ·l -or- L.A. = Πrl • The surface area of a right cone is the sum of the lateral area and the area of the base. S.A. = L.A. + B
Homework #27 • Due Thurs/Fri (Apr 11/12) • Page 620 – 621 • # 1 – 21 all
Section 11.4 – Volumes of Prisms and Cylinders • Objectives: To find the volume of a prism To find the volume of a cylinder
Volume the space that a figure occupies. It is measured in cubic units (, ). **Notice that volume and surface area are different. Surface area only includes the area of the container (empty soda can). Volume includes everything inside the container (full can of soda).**
Theorem 11.5 – Cavalieri’s Principle • If two space figures have the same height and the same cross-sectional area at every level, then they have the same volume.
Theorem 11.6 – Volume of a Prism • The volume of a prism is the product of the area of a base and the height of the prism. V = B · h h B
Theorem 11.7 – Volume of a Cylinder • The volume of a cylinder is the product of the area of the base and the height of the cylinder. V = B ·h -or- V = Πh r B h
Composite Space Figure a 3D figure that is the combination of two or more simpler figures. • Think of a rocket. It is composed of a conical top and a cylindrical body. The composite volume would be the volume of the cone added to the volume of the cylinder.
Section 11.5 – Volumes of Pyramids and Cones • Objectives: To find the volume of a pyramid To find the volume of a cone
Theorem 11.8 – Volume of a Pyramid • The volume of a pyramid is one third the product of the area of the base and the height of the pyramid. V = B · h
Theorem 11.9 – Volume of a Cone • The volume of a cone is one third the product of the area of the base and the height of the cone. V = B · h -or- V = h
Homework #28 • Due Monday (April 15) • Page 627 – 628 • # 1 – 19 odd • Homework #29 • Due Monday (April 15) • Page 634 – 635 • # 1 – 19 odd Quiz Tuesday
Section 11.6 – Surface Areas and Volumes of Spheres • Objectives: To find the surface area and volume of a sphere
Sphere the set of all points in space equidistant from a given point called the center. • Radius a segment that has one endpoint at the center and the other endpoint on the sphere • Diameter a segment passing through the center with endpoints on the sphere
When a plane and a sphere intersect in more than one point, the intersection is a circle. If the center of the circle is also the center of the sphere, the circle is called a great circle. • Circumference of the great circle is the same as the sphere • Hemispheres two equal halves of a sphere. These are created by a great circle.
Theorem 11.10 – Surface Area of a Sphere • The surface area of a sphere is four times the product of Π and the square of the radius of the sphere. S.A. = 4Π
Theorem 11.11 – Volume of a Sphere • The volume of a sphere is four thirds the product of Π (pi) and the cube of the radius of the sphere. V = Π
Ex: Earth’s equator is about 24,902 mi long. Approximate the surface area of Earth by finding the surface area of a sphere with circumference 24,902 mi. • Ex: The volume of a sphere is 4200 . Find the surface area to the nearest tenth.
Homework #30 • Due Monday (April 22) • Page 640 – 641 • # 1 – 21 all
Section 11.7 – Areas and Volumes of Similar Solids • Objectives: To find relationships between the ratios of the areas and volumes of similar solids
Similar Solids have the same shape, and all their corresponding dimensions are proportional. • Similarity Ratio the ratio of corresponding linear dimensions of two similar solids. **Any two cubes are similar and any two spheres are similar**
Ex: Identifying Similar Solids • Are the following figures similar? 3 6 2 3 4 6 6 5 12 10