3/29/12 How do we find the the surface area and lateral area of pyramids and cones?

How do we find the surface area and lateral area of pyramids and cones?

 Pyramids
- a pyramid is a solid that connects a polygon base to a point
- the slant height of a pyramid is the height of the lateral faces
Ex :

- you can calulate the lateral area of a pyramid by using the formula LA= 1/2pl
-'p' represents the perimeter
-'l' represents the slant height
- You can calculate the surface area


Cones
- the base of a cone is circle and the other end ( vertex) is pointed similar to a pyramid
- the slant height of a cone is the distance from the vertex to a point on the base
Ex:

- to calculate the lateral area of a cone use the formula (pi)rl
- 'r' represents the radius
-'l' represents the slant height
- In order to calculate the surface area , and extra steps need to be included
- use the formula SA= LA(lateral area) + B (base)
- to find the base use (pi)r^2 , then plug in the final number in the formula above this one

Practice Question: If the radius of a cone 'r' is 4 and the slant height 'l' is 12 , What is the the lateral area of a cone?










                                                         Citations
- Geometry help!!! triangular pyramid , MHF,http://mathhelpforum.com/geometry/27562-solved-geometry-help-triangular-pyramid.html , 2005-2012

- Ring my bell- Volume of cone , Lesson poly , Silicon valley education foundation, http://www.lessonopoly.org/node/2299 , 2010