1. By: John Cao & Colby Le

2.  Find lateral areas of cones  Find surface areas of cones

3.  A cone’s base is a circle and its vertex is referred to as point V.  The axis of a cone is the segment with endpoints at the vertex and the center of the base.  A segment that has one endpoint at the vertex and is perpendicular to the base is called the altitude of the cone.

4.  Right Cone - A cone that has an altitude that is also it’s axis.  Oblique Cone – A cone that has an altitude that is not it’s axis.  The measure of any segment from the vertex of a right cone to the edge of the base is the slant height, l.  The measure of the altitude is the height, h.

5.  The lateral area of a cone is the sector of a circle with radius l, the slant height of the cone.  The arc length of the sector of the circle is the same as the circumference of the base, or 2π r.  The circumference of the circle containing the sector is 2π l.  Using this information, you can create a formula to find the lateral area of the cone.  Formula: area of sector = π rl

6. 1.) If you have a cone whose base radius is 5 units and it’s slant height is 10 units, find the lateral area of the cone. Round to the nearest tenth. area of sector = π rl area of sector = π(5)(10) a.) area of sector ~ 157.1 units 2

7.  A cone has a base radius of 8 units and a slant height of 6 units. What is the lateral area of that cone to the nearest tenth? a.) area of sector ~ 150.8 units 2

8.  The total surface area of a cone is represented by T.  To find the surface area of a cone, add the area of the base to the lateral area of the cone.  Formula: T = π rl + π r 2

9. 2.) Find the surface area of a cone if its base radius is 3 units and its slant height is 4 units. Round to the nearest tenth. T = π rl + π r 2 T = π(3)(4) + π(3) 2 a.) T ~ 66.0 units 2

10.  A cone has a slant height of 7 units and a base radius of 5 units. Find the surface area of the cone to the nearest tenth. a.) T ~ 188.5 units 2

11.  Find the surface area of a cone to the nearest tenth if it has a base radius of 2 and a slant height of 13. a.) T ~ 94.2 units 2

12. page 668-669 #7-22