**Vocabulary**

center of a circle, circle, diameter, radius

**Parts of a Circle**

A **circle** is the set of all points in a plane that are the same distance from a given point called the center. You name a **circle** by its center. Circle *P* is shown.

A **diameter** is a segment that passes through the center of a circle and has both endpoints on the circle. The term *diameter* can also mean the length of this segment.

A **radius** is a segment that has one endpoint at the center and the other endpoint on the circle. The term *radius* can also mean the length of this segment.

**TEKS** 7(1)(E), 7(9)(B)

**Intro**

You name a segment by its endpoints. Read
*AB*.” The diagram shows

To refer to the length of a segment, you write the letters without the segment bar. So *AB* = 3 inches and *AC* = 3 inches.

**Example Naming Diameters and Radii of Circles**

An art class developed this logo to represent the school in an art show. Determine which segments are *radii* and which are *diameters*.

Digits, Grade 7, Volume 1, Homework Helper
Unit A: Number and Operations
Math Symbols
Formulas Measures
Properties

Topic 1: Operations with Rational Numbers

Unit B: Expressions, Equations, and Relationships
- 1-1: Rational Numbers, Opposites, and Absolute Value
- 1-1: TEKS Practice
- 1-2: Adding Rational Numbers
- 1-2: TEKS Practice
- 1-3: Subtracting Rational Numbers
- 1-3: TEKS Practice
- 1-4: Multiplying Rational Numbers
- 1-4: TEKS Practice
- 1-5: Dividing Rational Numbers
- 1-5: TEKS Practice
- 1-6: Operations With Rational Numbers
- 1-6: TEKS Practice
- 1-7: Additional Problem Solving
- 1-7: TEKS Practice

Topic 2: Equations & Inequalities

Unit C: Measurement and Geometry
- 2-1: Solving Simple Equations
- 2-1: TEKS Practice
- 2-2: Writing Two-Step Equations
- 2-2: TEKS Practice
- 2-3: Solving Two-Step Equations
- 2-3: TEKS Practice
- 2-4: Solving Simple Inequalities
- 2-4: TEKS Practice
- 2-5: Solving Two-Step Inequalities
- 2-5: TEKS Practice
- 2-6: Writing Problem Situations
- 2-6: TEKS Practice
- 2-7: Additional Problem Solving
- 2-7: TEKS Practice

Topic 3: Angles
Topic 4: Circles
Topic 5: Surface Area and Volume

Unit D: Proportionality
- 3-1: Measuring Angles
- 3-1: TEKS Practice
- 3-2: Adjacent Angles
- 3-2: TEKS Practice
- 3-3: Complementary Angles
- 3-3: TEKS Practice
- 3-4: Supplementary Angles
- 3-4: TEKS Practice
- 3-5: Vertical Angles
- 3-5: TEKS Practice
- 3-6: Sum of the Angles in a Triangle
- 3-6: TEKS Practice
- 3-7: Additional Problem Solving
- 3-6: TEKS Practice

- 4-1: Center, Radius, and Diameter
- 4-1: TEKS Practice
- 4-2: Circumference of a Circle
- 4-2: TEKS Practice
- 4-3: Area of a Circle
- 4-3: TEKS Practice
- 4-4: Areas of Semicircles and Quarter Circles
- 4-4: TEKS Practice
- 4-5: Area of Composite Figures
- 4-5: TEKS Practice
- 4-6: Additional Problem Solving
- 4-6: TEKS Practice

Topic 6: Ratios and Rates
Topic 7: Proportional Relationships
Topic 8: Representing Linear Relationships
Topic 9: Percents

English/Spanish Glossary
Formulas
- 9-1: The Percent Equation
- 9-1: TEKS Practice
- 9-2: Using the Percent Equation
- 9-2: TEKS Practice
- 9-3: Simple Interest
- 9-3: TEKS Practice
- 9-4: Compound Interest
- 9-4: TEKS Practice
- 9-5: Percent Increase and Decrease
- 9-5: TEKS Practice
- 9-6: Markups and Markdowns
- 9-6: TEKS Practice
- 9-7: Additional Problem Solving
- 9-7: TEKS Practice