1. Cross-sections, Rotations, and Geometric Nets
Secondary Math 3 – Section 8.1

2. Names of Shapes
Circle Square Rectangle Triangle Trapezoid Pentagon Hexagon Ellipse Octagon

3. Names of Solids
Cube Prism Cylinder Sphere Pyramid Cone

4. What is a cross-section?

5. Identify the cross-section of this solid.
Correct Answer: H

6. Identify the cross-section of this solid.
Correct Answer: H

7. Identify the cross-section of this solid.
Correct Answer: H

8. Identify the cross-section of this solid.
Correct Answer: D (B if vertical)

9. Identify the cross-section of this solid.
Correct Answer: F

10. Challenge Question
Can you cut the cube with a plane and create a cross-section with:
a) 3 sides b) 4 sides
c) 5 sides d) 6 sides
e) 7 sides f) 8 sides
Cross-section Simulator
a) yes; b) yes; c) yes; d) yes; e) no; f) no
Since the cube has six faces (sides) only a six sided cross-section can be formed.
Click on the link to see a way to visualize the cross-sections.

11. Geometric Nets – Example 1
Geometric nets describe the solid if it were “unfolded”

12. Geometric Nets – Example 2

13. Geometric Nets – Example 3

14. Two-dimensional Rotations
What would happen if we rotated the function 𝑓 𝑥 = 1 4 𝑥 around the y-axis?
If you shaded between the y-axis and f(x) and then rotated it around the y-axis you would have a cone. Radius would be 4 and height would be 1.

15. Two-dimensional Rotations
What would you have to rotate to obtain this 3- dimensional solid?
If you rotated a circle around a line not touching the circle you could create this donut.