Lesson 21 — Activity 3: Planes of Symmetry
Completion requirements
Lesson 21 — Activity 3: Planes of Symmetry
Getting Ready
So far in this lesson, you have looked at symmetry in two-dimensional objects. Three-dimensional objects can also be symmetrical. If you were to draw a line down the middle of your body, from the top of your head to the bottom of your feet and look at it, you would find that your body is almost symmetrical.
In this activity, you will look at planes of symmetry. A plane of symmetry is an imaginary line that creates two congruent (equal) three-dimensional pieces that are reflections of each other.
Here is an example showing planes of symmetry in a rectangular prism. A rectangular prism has three planes of symmetry. Each cuts the object into two equal pieces.
Let's now look at a cube. How many ways do you think you could cut a cube so that each part was a mirror image (exact reflection) of the other part?
Click here to view the planes of symmetry for a cube. As you can see, there are nine different planes of symmetry in a cube. You will practise creating these planes in the assignment on the next page.Images courtesy of www.imagesgoogle.com and K&E Studio.
Let's now look at a cube. How many ways do you think you could cut a cube so that each part was a mirror image (exact reflection) of the other part?
Click here to view the planes of symmetry for a cube. As you can see, there are nine different planes of symmetry in a cube. You will practise creating these planes in the assignment on the next page.
Click here to view the planes of symmetry for a cube. As you can see, there are nine different planes of symmetry in a cube. You will practise creating these planes in the assignment on the next page.