Unit 6 · Similarity and Dilations

6.9Applications of Similarity

Quick Answer

Similarity is used in indirect measurement (shadow method, mirror method), scale drawings, and map reading. If two figures are similar with scale factor k, their perimeters have ratio k and their areas have ratio k².

Essential Question

How can similar triangles be used to measure distances and heights that cannot be measured directly?

Learning Goals

  • 1Use similar triangles for indirect measurement.
  • 2Interpret scale drawings and maps.
  • 3Apply the perimeter ratio (k) and area ratio (k²) for similar figures.
  • 4Solve real-world problems using similarity.

Key Vocabulary

Indirect measurement

Using similar triangles to find a length that cannot be measured directly.

Scale drawing

A drawing in which all lengths are proportional to the actual lengths by a constant scale factor.

Full lesson content coming soon

Worked examples, guided practice problems, a workbook, quiz, and downloadable PDF resources will be added to this lesson in Phase 2. The learning goals and vocabulary above reflect the complete lesson scope.