



A
regular pyramid is one with a square base



and four
triangles for sides. 


These
triangles all have 2 sides that are the same length. 


That
makes them something called isosceles triangles. 











We don't
know enough math tricks yet 


to show
you where the formula 


for the
volume of a pyramid comes from. 


We have
to just list it ... 











Example: 


What is
the volume of a pyramid 


with
these dimensions ... 











To find
the area of the surface of the pyramid, 


we need
one more measurement. 





That
measurement is called the slant height. 





This is
the height of the triangles 


that make
the sides of the pyramid. 





Since the
triangle lives on an angle, 


we call
the height the slant height. 











Example: 


Find the
area of the surface of the pyramid. 











The area
of the base is: 


8 ×
8 = 64



(Sometimes
we need this area, sometimes we don't)






The 4
sides of the triangles look like this: 











Each of
these triangles are made up of 2 triangles. 


Like this
... 











There are
2 triangles in each of the 4 sides of the pyramid. 


So the
area is ... 





Area
= 2 triangles per side ×
4 sides ×
14



Area = 2 ×
4 ×
14 


Area = 112 





If the
area of the base is added, the total area is: 





Area
= 112 + 64 


Area
= 176 





copyright 2005 Bruce Kirkpatrick 
