Unit 10 · Measurement and Three-Dimensional Geometry

10.4Composite Figures

Quick Answer

To find the area of a composite figure, decompose it into simpler shapes (rectangles, triangles, semicircles), find each area, then add or subtract as needed.

Essential Question

How does decomposing a complex figure into simpler shapes make it possible to find its area using formulas you already know?

Learning Goals

  • 1Identify the simpler shapes that make up a composite figure.
  • 2Add areas to find the total area of a composite figure.
  • 3Subtract areas when a region is removed from a larger shape.
  • 4Find the perimeter of a composite figure by tracing its boundary.

Key Vocabulary

Composite figure

A figure made up of two or more simple geometric shapes.

Area addition

Finding the total area of a composite figure by summing the areas of its parts.

Area subtraction

Finding the area of a figure with a hole by subtracting the removed area from the total.

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.