1. A polyhedron has 6 vertices and 9 edges. How many faces does it have?

A. 3
B. 5
C. 7
D. 9

2. A polyhedron has 25 faces and 36 edges. How many vertices does it have?

A. 11
B. 12
C. 13
D. 14

3. What is the cross section formed by a plane that contains a vertical line of symmetry for a tetrahedron?

A. triangle
B. square
C. rectangle
D. pentagon

4. What is the cross section formed by a plane that intersects three faces of a cube?

A. triangle
B. square
C. rectangle
D. pentagon

Respuesta :

Hello Madoudou!

#1

So we have:

F which is the number of faces we are looking for

E which are the numbers of edges

and V the number of vertices

We can use the Euler's polyhedron formula. Which is:

V - E + F = 2

Remember we are solving for F. Thus,

F = E - V + 2

F = 9 - 6 + 2

F = 9 - 4

F = 5

The correct answer is option B

#2

It is almost the same problem. They just want us to find the vertices.

V = E - F + 2

V = 36 - 25 + 2

V = 36 - 23

V = 13

The correct answer is option C

#3

The cross section formed by a plane that contains a vertical line of symmetry for a tetrahedron is a Triangle.

The correct answer is option A

#4

The cross section formed by a plane that intersects three faces of a cube is a Triangle.

The correct answer is option A


Let me know if you have any questions about the answers. As always, it is my pleasure to help students like you.





Polyhedron is three-dimensional solid which consist collection of polygons joint with edges.

  • The option B is the correct option for problem 1.
  • The option C is the correct option for problem 2.
  • The option A is the correct option for problem 3.
  • The option A is the correct option for problem 4.

Polyhedron

Polyhedron is three-dimensional solid which consist collection of polygons joint with edges.

The Euler's formula between the vertex, edges and faces can be given as,

[tex]F+V=E+2[/tex]

Here [tex]F[/tex] is the number of faces, [tex]V[/tex] is the number of the vertex and [tex]E[/tex] is the number of edges of the polyhedron.

1) The polyhedron which has 6 vertices and 9 edges,

Use the Euler's formula to find the faces as,

[tex]\begin{aligned}\\ F+V&=E+2\\ F+6&=9+2\\ F&=11-6\\ F&=5\\ \end[/tex]

Thus the polyhedron which has 6 vertices and 9 edges has 5 number of faces. The option B is the correct option for problem 1.

2) The polyhedron which has 25 faces and 36 edges,

Use the Euler's formula to find the faces as,

[tex]\begin{aligned}\\F+V&=E+2\\25+V&=36+2\\V&=38-25\\V&=13\\\end[/tex]

Thus the polyhedron which has 25 faces and 36 edges has 13 number of vertex. The option C is the correct option for problem 2.

3) The cross section formed by a plane that contains a vertical line of symmetry for a tetrahedron-

Tetrahedron is a triangular pyramid with four triangular faces. Thus The cross section formed by vertical line contained plane of symmetry for a tetrahedron is triangle. Thus The option A is the correct option for problem 3.

4) The cross section formed by a plane that intersects three faces of a cube-

When a plane intersect the cube with three of its faces the cross section of that plane is a triangle. Thus The option A is the correct option for problem 4.

Hence,

  • The option B is the correct option for problem 1.
  • The option C is the correct option for problem 2.
  • The option A is the correct option for problem 3.
  • The option A is the correct option for problem 4.

Learn more about the polyhedron here;

https://brainly.com/question/10732990