Question

If a polyhedron has 5 faces and 7 vertices, then it must have how many edges? Please show step-by-step work

Answer 1

Answer:

10 edges

Step-by-step explanation:

we know that

The Euler's formula state that: In a polyhedron, the number of vertices, minus the number of edges, plus the number of faces, is equal to two

$V - E + F = 2$

in this problem  we have

$V=7\\E=?\\F=5$

substitute the given values

$7 - E + 5 = 2$

solve for E

Combine like terms in the left side

$12 - E = 2$

subtract 12 both sides

$- E = -10$

Multiply by -1 both sides

$E =10$