Circles: Radius, Diameter, Circumference & Area | 7.G.B.4 | Grade 7 Math 💚

In this math video we will learn about circles, radius, diameter, circumference and area. We will review the definition of circle and how to identify the radius and diameter. A circle is the set of all points in a plane that are the same distance from a given point called the center. A radius is the distance from the center of a circle to any point on the circle. A diameter is the distance across a circle through its center. We will understand the relationship between the radius and the diameter. We find the radius of a circle given the diameter. We will find the diameter of a circle given the radius. We will learn the formula for the area of a circle - A=pi times r squared. We will find the area of circle given the radius. We will find the area of a circle using 3.14 for pi and in terms of pi. We will also find the area of a circle given the diameter. We will then learn the formulas or circumference of a circle; C=2 times pi times r and C= pi times d. We will find the circumference of a circle given the diameter and given the radius. We will find the radius of a circle given the circumference. Student practice is embedded in the lesson. Exemplar solutions are modeled and explained.

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00:00 Introduction
00:18 Lesson Objectives
00:40 Essential Question
01:00 Vocabulary - circle, radius, diameter
02:39 Relationship between Radius & Diameter
03:48 Student Practice #1
04:48 Student Practice #2
05:26 Area of a Circle
06:27 Area in terms of Pi & Using 3.14
08:45 Finding Area Using Diameter
10:30 Student Practice #3
11:44 Circumference of a Circle
12:48 Using C=2(pi)r
13:36 Student Practice #4
14:30 Finding the Area given Circumference
14:48 Solution

Geometry
7.G.B.4 Know the formulas for the area and circumference of a circle and use them to solve problems; give an informal derivation of the relationship between the circumference and area of a circle.