1. Please clear off your desks except for your homework, opening activity, pen/pencil and calculator!!! Opening Activity: 1. Find the volume of the following rectangular pyramid: 11cm 14cm 8cm

2. Chapter 8 Lesson 6 Surface Area of Prisms

3. Objective: Students will find the surface areas of prisms.

4. The surface area S.A. of a rectangular prism with base l, width w. and height h is the sum of the areas of its faces. l w h S.A. = 2lh + 2lw +2hw When you find the surface area of a three-dimensional figure, the units are square units.

5. Example 1: Find the surface area of the rectangular prism. 10m 3m 6m S.A.= 2lh + 2lw + 2hwSurface area of a rectangular prism = 2(10)(6)+2(10)(3)+2(6)(3)

6. Example 2: Find the surface area of the rectangular prism. 11mm This is a cube, so all sides are equal. In this case, you can find the area of one side and multiply it by 6 since a cube has six sides. S.A.= 6(11)(11)

7. Example 3: Find the surface area of the rectangular prism. 6cm 2 cm 3 cm S.A. = 2lh + 2lw + 2hw = 2(6)(3) + 2(6)(2) + 2(3)(2)

8. Example 4: The largest corrugated cardboard box ever constructed measured about 23 feet long, 9 feet high, and 8 feet wide. Would 950 square feet of paper be enough to cover the box? Justify your answer. 23 ft 9ft 8 ft Draw a picture S.A. = 2lh + 2lw + 2hw =2(23)(9) + 2(23)(8) +2(9)(8) The surface area of the box is 926 square feet. Since 950 square feet >926 square feet, there is enough paper to cover the box.

9. To find the surface area of a triangular prism, find the area of each face and calculate the sum of all of the faces rather than using a formula. 4 in 3in 14 in The triangular prism can be broken up into its 5 faces and the areas of all the faces can be calculated and then added together. 3in 4 in 3.6 in 14in 3.6in 14in 4in 14in Triangles: Side faces: Bottom face: Add the areas together to get the total surface area:

10. Example 5: Find the surface area of the triangular prism. 2cm 3cm 4cm 2.5cm Triangles: 2 side faces: Bottom face: To get the total surface area add all the face areas together:

11. Example 6: Brian’s tent is a triangular prism. How much fabric was used to make the tent? 7ft 10 ft 12 ft 8.6 ft Triangles: 2 side faces: Bottom face: To get the total surface area of the triangular prism, add the area of all the faces together:

12. Lesson Essential Question: Why is the surface area of a three dimensional figure measured in square units instead of cubic units?