Posted by Fustrated on Monday, February 6, 2012 at 9:37pm.
The base of a regular pyramid is a square whose sides have a length 8 cm. If a lateral edge of this pyramid has length 20 cm, what is the surface area of the pyramid?

math  Reiny, Monday, February 6, 2012 at 9:53pm
Look at one of the triangles, which is isosceles with a base of 8 and each of the equal sides of length 20
Height of triangle: let it be h
h^2 + 4^2 = 20^2
h^2 = 384
h = √384
Area of one triangle = (1/2)(8)(√384) = 4√384
Assuming the surface area consists only of the 4 triangles,
surface area = 4(4√384) or 16(8√6) = 128√6

math  Fustrated, Monday, February 6, 2012 at 10:07pm
Thanks, but I need the base too  that I can do by myself!
Answer This Question
Related Questions
 Geometry  The base of a regular pyramid is a hexagon whose sides have length 5 ...
 Mathematics  OPQRS is a right pyramid whose base is a square of sides 12cm each...
 Maths  OPQRS is a right pyramid whose base is a square of sides 12cm each. ...
 Maths  OPQRS is a right pyramid whose base is a square of sides 12cm each. ...
 math  A truncated square pyramid (also known as a frustum) is an object ...
 geometry  Identify the lateral area and surface area of a regular square ...
 MATH! PLEASE REPLY ASAP!  OPQRS is a regular squarepyramid whose base has ...
 Math  A square pyramid each side of the base has a length of 60 m and the ...
 Math  Ira built a model of the great pyramid in Egypt for a school project. The...
 geometry  A pyramid has a square base with each side measuring 105.5 meters. ...
More Related Questions