4.9 Circles
About Circles
I.SectionObjectives
- Distinguish between radius, diameter, chord, tangent, and secant of a circle.
- Find relationships between congruent and similar circles.
- Examine inscribed and circumscribed polygons.
- Write the equation of a circle.
II.MultipleIntelligences
- To differentiate this lesson, break the lesson down into two sections. In the first section, cover all of the basic
information about circles. - Have the students work on creating a diagram of a circle. Their diagram must have the following things
labeled: radius, chord, diameter, secant, tangent line. - Encourage students to make their diagrams colorful.
- Allow time for sharing when students are finished.
- The second part of the lesson involves more of the operations associated with circles.
- For this lesson, be sure that students have graph paper to work with.
- Complete the examples on the board and walk through each of the examples and all of the steps needed to
complete each one. - Point out where to find the radius and the ordered pair in the equation.
- Make this section interactive so that you work through the example on the board/overhead while the students
work through it in their notebooks. - Working through this as a whole class will help the students to follow the steps of each problem.
- Intelligences- linguistic, visual- spatial, logical- mathematical, interpersonal, intrapersonal.
III.SpecialNeeds/Modifications
- Include the following notes for students.
- Two circles are congruent if they have the same radius. Two circles are similar if they have different radii.
Their similarity is shown through a ratio. - When writing similarity ratios be sure to simplify.
- Remember that you can write the ratios in three ways. The text uses a colon, but you can use a fraction or the
word “to”. - Define chord.
- Define diameter.
- Define secant.
- Tangent line- touches a circle at one point. This is called the point of tangency.
- Inscribed polygon- convex polygon inside circle.
- Circumscribed polygon- convex polygon around circle.
- Review convex polygons.
- Equations with graphing- work through slowly.
Chapter 4. Geometry TE - Differentiated Instruction