A rectangular prism is a threedimensional object characterized by six rectangular faces, two of which are considered to be the bases of the prism. Rectangular prisms are commonly seen in the real world in the form of cardboard boxes, toy chests and food packaging. The number of edges, or sharp sides formed by the intersection of two faces, can be found using a mathematical formula called Euler's formula. Euler's formula states that VE+F=2, or vertices minus edges plus faces equals two.
Things You'll Need
 Paper
 Pencil

Write Euler's formula in your notebook using the following format: VE+F=2.

Rewrite the formula so that "E," the unknown variable, is alone on one side of the equation. This can be done in two steps. First, move the "E" to the opposite side of the equation to make it a positive; write V+F=E+2 beneath the original equation. Next, move the "2" to the left side of the equation so that the "E" stands alone on the right. When the "2" is moved, it becomes a negative, and so the next line in your notebook should be written as V+F2=E.

Input numbers for the variables that are known  in this case, vertices and faces. For example, if the prism has eight vertices and six faces, the formula will be rewritten as 8+62=E.

Solve the equation. In this case, the equation will be rewritten as 12=E or E=12, meaning that the number of edges in a rectangular prism is 12.
Tips & Warnings
 Use Euler's formula to find the number of vertices, faces or edges on various threedimensional solids.
References
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