1. 12.3 Surface Area of a Pyramids and Cones Slant Height ( l )

2. Definition of a Regular Pyramids A regular pyramid is a pyramid whose base is a regular polygon and whose vertex forms a segment with the center of the polygon perpendicular to its plane.

3. Part of a Pyramid h is Height from base to vertex l is Slant height, The height of the triangle

4. Theorem Surface Area of a Regular Pyramid B is for base Area P is for perimeter l is for Slant height

5. Surface Area of a Regular Pyramid Let r = 3; h = 4 Find the Perimeter r is half the base edge

6. Surface Area of a Regular Pyramid Let r = 3; h = 4 Find the Perimeter r is half the base edge Base edge is 2(3) = 6 Square perimeter 4(6) = 24 P = 24

7. Surface Area of a Regular Pyramid Let r = 3; h = 4 ; P = 24 Find the Base Area

8. Surface Area of a Regular Pyramid Let r = 3; h = 4 ; P = 24 ; B = 36 Find the Base Area Base edge is 6 Base Area = (6) 2 B = 36

9. Surface Area of a Regular Pyramid Let r = 3; h = 4 ; P = 24 ; B = 36 Find the Slant Height l Right Triangle

10. Surface Area of a Regular Pyramid Let r = 3; h = 4 ; P = 24 ; B = 36 ; l = 5 Find the Slant Height l Right Triangle side legs 3 and 4 3 2 + 4 2 = l 2 9 + 16 = 25 = l 2 l = 5

11. Surface Area of a Regular Pyramid Let r = 3; h = 4 ; P = 24 ; B = 36 ; l = 5

12. Surface Area of a Regular Pyramid Let r = 4; h = ; P = 24 ; B = ; l = 9 Find the Base and Perimeter

13. Surface Area of a Regular Pyramid Let r = 4; h = ; P = 24 ; B = ; l = 9 Find the Base and Perimeter

14. Surface Area of a Regular Pyramid Let r = 4; h = ; P = 24 ; B = ; l = 9 Find the Surface Area

15. Surface Area of a Regular Pyramid Let r = 4; h = ; P = 24 ; B = ; l = 9 Find the Surface Area

16. Surface of a Cone Finding the Base is Easier, since it is a circle.

17. Surface of a Cone Finding the Surface Area. r = 5, h = 12

18. Surface of a Cone Finding the Surface Area. r = 5, h = 12; need l

19. Surface of a Cone Finding the Surface Area. r = 5, h = 12; need l

20. Surface of a Cone Finding the Surface Area. r = 5, h = 12; need l

21. Homework Page 738-741 #15 – 43 odd

22. Homework Page 738-741 #14 - 38 even, 44 - 46