Summary: Solving Problems With Circles and Irregular Figures

• Circumference of a Circle
• Area of a Circle
• Area of an L-shaped polygon
• Area of an L-shaped polygon with Decimals
• Perimeter Involving a Rectangle and Circle
• Area Involving a Rectangle and Circle

Key Concepts

• Problem Solving Strategy for Geometry Applications
  1. Read the problem and make sure you understand all the words and ideas. Draw the figure and label it with the given information.
  2. Identify what you are looking for.
  3. Name what you are looking for. Choose a variable to represent that quantity.
  4. Translate into an equation by writing the appropriate formula or model for the situation. Substitute in the given information.
  5. Solve the equation using good algebra techniques.
  6. Check the answer in the problem and make sure it makes sense.
  7. Answer the question with a complete sentence.
• Properties of Circles
  • [latex]d=2r[/latex]
  • Circumference: [latex]C=2\pi r[/latex] or [latex]C=\pi d[/latex]
  • Area: [latex]A=\pi {r}^{2}[/latex]

Glossary

irregular figure

An irregular figure is a figure that is not a standard geometric shape. Its area cannot be calculated using any of the standard area formulas.

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