PSAT Math : How to find the length of an edge of a tetrahedron

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #71 : Solid Geometry


Refer to the above tetrahedron, or four-faced solid. The surface area of the tetrahedron is 444. Evaluate  to the nearest tenth. 

Possible Answers:

Correct answer:


The tetrahedron has four faces, each of which is an equilateral triangle with sidelength . Since the total surface area is 444, each triangle has area one fourth of this, or 111. To find , set  in the formula for the area of an equilateral triangle:

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