Questions on Geometry: Polygons answered by real tutors!

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Question 144737: what is the approximate srface area of a regular tetrahedron with edge length 12 cm? : what is the approximate srface area of a regular tetrahedron with edge length 12 cm?
Answer by Alan3354(1449) About Me  (Show Source):
You can put this solution on YOUR website!
A regular tetrahedron is composed of 4 triangular faces, here all sides are 12"
The area of a triangle is 1/2 of base times height, bh/2.
The height is sqrt(12^2-6^2)
h = sqrt(108)
The area of 1 triangle is 12sqrt(108)/2
The total is 4 times this, or 24sqrt(108)
Area = 249.415 square cm