# Ch 10: Big Ideas Math Geometry Chapter 10: Circles

### About This Chapter

## How It Works:

- Find the lesson within this chapter that corresponds to what you're studying in the Circles chapter of your textbook.
- Watch fun videos that cover the circle concepts you need to learn or review.
- Complete the quiz after watching each video lesson to test your understanding.
- If you need additional help, rewatch the videos until you've mastered the material, or submit a question for one of our instructors.

## Chapter Topics

You'll learn all of the geometry topics covered in the textbook chapter, including:

- What the parts of a circle are
- Measuring the arc of a circle
- The formula for determining the chord of a circle
- What inscribed and circumscribed angles are
- Determining the equation of a circle
- How to write coordinate proofs for circles

*Big Ideas Math is a registered trademark of Larson Texts, Inc., which is not affiliated with Study.com.*

### 1. Parts of a Circle

After watching this video lesson, you will be able to identify the parts of a circle. You will learn the names of four different parts of a circle along with what each part does for the circle.

### 2. Tangent of a Circle: Definition & Theorems

What happens when a line just barely touches a circle? It's a tangent! In this lesson, we'll learn all about tangents to circles, including a few key theorems. We'll also look at tangent circles.

### 3. Measure of an Arc: Process & Practice

What is the measure of an arc? And what is the difference between a minor arc and a major arc? Find out all that and practice finding the measure of an arc in this lesson.

### 4. Chord of a Circle: Definition & Formula

In this lesson, you'll learn the definition of a chord of a circle. You will also learn the formulas to find the chord of a circle and then look at some examples.

### 5. How to Find the Measure of an Inscribed Angle

Finding the measure of an inscribed angle requires knowing a little information. In this lesson, we'll find the measure of an inscribed angle when we know the measure of the central angle or one or more of the arcs formed by the angle.

### 6. Inscribed and Circumscribed Figures: Definition & Construction

A square and a circle may be different shapes, but they still can have a unique relationship. In this lesson, we'll learn about inscribed and circumscribed figures.

### 7. Theorems of Finding Angle & Arc Measures

This lesson explains how to find angle and arc measures. The following theorems are discussed: tangent and intersected chord theorem, angles inside a circle theorem and angles outside a circle theorem.

### 8. Circumscribed Angle: Definition & Theorem

Geometry involves many different shapes. In this lesson, we will deal with a circle and two lines tangent to the circle. This forms a circumscribed angle, which we will learn how to identify and how to calculate its angle.

### 9. Measurements of Angles Involving Tangents, Chords & Secants

When lines and circles meet, angles are formed. Fortunately, we can determine the measure of these angles, whether they're formed by tangents, secants or chords, just by knowing the measure of the created arcs.

### 10. Measurements of Lengths Involving Tangents, Chords and Secants

The lengths of chords, tangents and secants take on unique relationships when they're drawn on circles. In this lesson, we'll define those relationships and see them in action.

### 11. How to Find the Equation of a Circle

There are two commonly used forms of equations for a circle, in this lesson we'll take a few minutes to examine and understand both forms, and be able to convert from one to the other.

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### Other Chapters

Other chapters within the Big Ideas Math Geometry: Online Textbook Help course

- Big Ideas Math Geometry Chapter 1: Basics of Geometry
- Big Ideas Math Geometry Chapter 2: Reasoning and Proofs
- Big Ideas Math Geometry Chapter 3: Parallel and Perpendicular Lines
- Big Ideas Math Geometry Chapter 4: Transformations
- Big Ideas Math Geometry Chapter 5: Congruent Triangles
- Big Ideas Math Geometry Chapter 6: Relationships Within Triangles
- Big Ideas Math Geometry Chapter 7: Quadrilaterals and Other Polygons
- Big Ideas Math Geometry Chapter 8: Similarity
- Big Ideas Math Geometry Chapter 9: Right Triangles and Trigonometry
- Big Ideas Math Geometry Chapter 11: Circumference, Area, and Volume
- Big Ideas Math Geometry Chapter 12: Probability