SOLUTION: the total area of a regular dodecahedron is 288 square root of 3 inches squared, find the measure of an edge.

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Question 1087817: the total area of a regular dodecahedron is 288 square root of 3 inches squared, find the measure of an edge.
Answer by Edwin McCravy(20055) About Me  (Show Source):
You can put this solution on YOUR website!
Here's how a regular dodecahedron looks:
 
All 12 faces of a regular dodecahedron are 
congruent regular pentagons:  



The area of a regular pentagon is given by the formula



[If you don't know this formula, then ask me how to get it
in the thank-you note form below and I'll get back to you
by email.]

All 12 faces of the regular dodecahedron together have area 12
times that or

3sqrt%285%285%2B2sqrt%285%29%29%29%2Aedge

Thus in this case,

3sqrt%285%285%2B2sqrt%285%29%29%29%2Aedge%22%22=%22%22288

sqrt%285%285%2B2sqrt%285%29%29%29%2Aedge%22%22=%22%2296 

edge%22%22=%22%2296%2Fsqrt%285%285%2B2sqrt%285%29%29%29

Rationalizing the denominator gives:

edge%22%22=%22%22expr%2896%2F5%29sqrt%285-2sqrt%285%29%29

Edwin