# Cross Section

Pronunciation: /ˈkrɔs ˈsɛk.ʃən/ Explain

 Figure 1: Stack of coins.
1. In geometry, a cross section is a section made by cutting an object with a plane. Cross sections are important in the study of math. Cavalieri's principle states that, if the volumes of the cross sections of two 3-dimensional geometric figures are equal, then the volumes of the two figures is the same. This is illustrated by a stack of coins. It doesn't matter how the coins are stacked, the volume of the stack of coins remains the same. Cavalieri's principle leads the way to infinitesimal calculus.
2. In statistics, a cross section is a sample of data believed to be representative.

### Examples of Geometric Cross Sections

 Figure 1: Cross section of a tree trunk.

 Figure 2: Cross section of a car engine.

 Figure 3: Cross section of the earth's crust.

### References

1. McAdams, David E.. All Math Words Dictionary, cross section. 2nd Classroom edition 20150108-4799968. pg 51. Life is a Story Problem LLC. January 8, 2015. Buy the book

McAdams, David E. Cross Section. 12/21/2018. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/c/crosssection.html.

### Image Credits

• Stacks of coins: Anton, http://commons.wikimedia.org. Licensed under the terms of the GNU Free Documentation License, Version 1.2 or any later version.