Indirect Measurement - Using Similar Triangles
Examples, solutions, videos, worksheets, stories, and songs to help Grade 8 students learn about indirect measurement (using similar triangles).
Indirect Measurement Using Similar Triangles
Indirect measurement is a method of using proportions to find an unknown length or distance in similar figures.
Two common ways to achieve indirect measurement involve
(1) using a mirror on the ground and
(2) using shadow lengths and find an object’s height.
Method 1 measures the person’s height and the distances between the person, mirror, and object.
Method 2 measures shadows and the person’s height.
Indirect Measurement: Examples
How to apply your knowledge of similar triangles and proportions to model real-life situations and to find unknown measurements indirectly.
Example:
- A tree outside Ellie’s building casts a 125 foot shadow. At the same time of day, Ellie casts a 5.5 foot shadow. If Ellie is 4 feet 10 inches tall, how tall is the tree?
- Cameron is 5 ft tall and casts a 12 ft shadow. At the same time of day, a nearby building casts a 78 ft shadow. How tall is the building?
- The Empire State Building is 1250 ft. tall. At 3:00, Pablo stands next to the building and has an 8 ft. shadow. If he is 6 ft tall, how long is the Empire State Building’s shadow at 3:00?
Indirect Measurement Using Similar Triangles
Indirect measurement of stadium lights using similar triangles with 3 methods: a mirror, a shadow, and a photograph.
Try the free Mathway calculator and
problem solver below to practice various math topics. Try the given examples, or type in your own
problem and check your answer with the step-by-step explanations.
We welcome your feedback, comments and questions about this site or page. Please submit your feedback or enquiries via our Feedback page.