Measurement Session 5: Measurement and Trigonometry

How do people determine lengths when they can't use standard measuring tools, such as a tape measure? How do they find the distance across a river if, for example, they don't have a boat? Measurements of very large objects or of long distances are often made indirectly, using similar triangles and proportions. Such indirect methods link measurement with geometry and number.

For information on required and/or optional materials for this session, see Note 1.

Part A:
Indirect Measurement With a Transit

Part B:
Measuring Heights of Tall Objects

Part C:
Steepness and Trigonometry

Homework

In this session, you will do the following:
•	Explore a number of methods for indirect measuring, such as using similar triangles, shadows, and transits
•	Learn about right-triangle trigonometry
•	Learn about the relationships between steepness, angle of elevation, and height-to-distance ratio (tangent ratio)
•	Use trigonometry ratios to solve problems involving right triangles


	Throughout the session you will be prompted to view short video segments. In addition to these excerpts, you may choose to watch the full-length video of this session.


	Previously Introduced:		New in This Session:
	ratio scale factor		proportion similar triangles tangent

Next > Part A: Indirect Measurement With a Transit

Session 5: Index | Notes | Solutions | Video