Circles

Lesson 10

Math

Unit 7

10th Grade

Lesson 10 of 14

Objective


Use angle and side length relationships with chords, tangents, inscribed angles, and circumscribed angles to solve problems. 

Common Core Standards


Core Standards

  • G.C.A.2 — Identify and describe relationships among inscribed angles, radii, and chords. Include the relationship between central, inscribed, and circumscribed angles; inscribed angles on a diameter are right angles; the radius of a circle is perpendicular to the tangent where the radius intersects the circle.

Criteria for Success


  1. Identify and use angle and segment relationships in circle diagrams to find missing measures. 
  2. State and describe the conjectures and theorems used to find missing measures in circle diagrams. 

Tips for Teachers


This lesson summarizes key concepts in the unit; therefore, this lesson should be used as a review day. 

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Anchor Problems


Problem 1

In circle $$A$$ below, $$\overleftrightarrow{CE}$$ and $$\overleftrightarrow{DE}$$ are tangent at points $$C$$ and $$D$$, respectively.

Find $$m\angle{CED}$$ and $$m\angle{ADG}$$.

Guiding Questions

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References

GeoGebra Geometry - 8.10 AP1

Geometry - 8.10 AP1 by Match Fishtank is made available by GeoGebra under the CC BY-NC-SA 3.0 license. Copyright © International GeoGebra Institute, 2013. Accessed June 13, 2017, 11:55 a.m..

Problem 2

In the following diagram, the radius of circle $$D$$ is $$5$$ cm and $$F$$ is the midpoint of $$\overline{AE}$$. The measures of $$\widehat{EB}$$ and $$\widehat{BC}$$ are given in the diagram. Find the measures of all other unmarked angles, arcs, and segments.

Guiding Questions

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References

Mathematics Vision Project: Geometry Module 7: Circles a Geometric PerspectiveLesson 6, "Circular Reasoning"

Module 7: Circles a Geometric Perspective from Geometry: A Learning Cycle Approach made available by Mathematics Vision Project under the CC BY 4.0 license. © 2016 Mathematics Vision Project. Accessed Oct. 19, 2017, 2:58 p.m..

Modified by Fishtank Learning, Inc.

Target Task


In the diagram below, $$\overline{PA}$$ is tangent to circle $$O$$, and $$\overline{AB}$$ is a chord. If $$m\widehat{ACB}=300$$, find the measure of $$\angle BAP$$.

References

JMAP G.C.A.2: Chords, Secants, and Tangents 17Question #2

G.C.A.2: Chords, Secants, and Tangents 17 is made available on JMAP by Steve Sibol and Steve Watson. Copyright © 2017  JMAP, Inc. - All rights reserved. Accessed Sept. 19, 2018, 10:43 a.m..

Additional Practice


The following resources include problems and activities aligned to the objective of the lesson that can be used for additional practice or to create your own problem set.

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Lesson 9

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Lesson 11

Lesson Map

A7CB09C2-D12F-4F55-80DB-37298FF0A765

Topic A: Equations of Circles

Topic B: Angle and Segment Relationships in Inscribed and Circumscribed Figures

Topic C: Arc Length, Radians, and Sector Area

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