Cross Sections
Concept
A plane section of a three-dimensional object is a two-dimensional slice formed by an intersection of the object with a plane. A cross-section is a plane section that is a section of a three-dimensional object that is parallel to one of its planes of symmetry or perpendicular to one of its lines of symmetry.
Rules
1. Slice the solid horizontally, vertically, or at an angle.
2. Identify the shape formed by the intersection of the plane and the solid.
Example
Which of the following is a cross section of the given solid figure?
Solution
When the figure is sliced horizontally, the cross section is a triangle.
Practice Cross Sections
Practice Problem 1
Which of the following is a cross section of the given solid figure?
Practice Problem 2
Which of the following is a cross section of the given solid figure?
Practice Problem 3
Which of the following is NOT a cross section of the given solid figure?
A cross section is the shape we get when cutting straight through an object.
Vertical Slice: When the plane is vertical to the solid’s base
Angled Slice: When the plane is at an angle to the solid’s base.
Horizontal Slice: When the plane is horizontal to the solid’s base.
Pre-requisite Skills
Identify Three Dimensional Figures
Faces, Edges, and Vertices
Nets of 3 Dimensional Figures