geometry/notes 10.1

SECTION 10.1Circles and Circumference

CIRCLES AND CIRCUMFERENCE

What are the parts of a circle? How can I solve problems using

circumference?

CIRCLE

Circle: The locus of all points in a plane equidistant from a given point called the center of the circle.

PARTS OF A CIRCLE

Name: from the center. Circle L or L

L

PARTS OF A CIRCLE

Radius: A segment with one endpoint in the center and the other on the circle.

L

M

PARTS OF A CIRCLE

Chord: A segment with both endpoints on the circle.

PARTS OF A CIRCLE

Diameter: A chord that passes through the center.

Relationship between radius and diameter?

G

H

EXAMPLES

1. Name the circle2. Name a radius3. Name a chord4. Name a diameter

EXAMPLE

Circle R has diameters and .1. If = 18, find 2. If = 24, find 3. If = 2, find

EXAMPLE

The diameter of X = 22 mm, Y = 16 mm, and Z = 10 mm. Find EZ and YF.

EXAMPLE

The diameter of D = 5 in, B = 9 in, and A = 18 in. Find BE and BC.

CIRCUMFERENCE

Circumference: The distance around a circle.

C =

C =

EXAMPLE

1. Find C if r = 13 inches1. Exact=2. Approximate =

2. Find C if d = 6 mm

3. Find d and r to the nearest hundredth if c = 65.4 feet.

HOMEWORK

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LESSON PLAN

Intro Circles!

Standards- Supplies – slides, whiteboard, note sheets Timing: Day 1 with notes and homework. A

second day will be review and a third with a quiz.

Essential Questions- slides 2 Input-slides 3-7 and 12 Guided Practice – slides 8-11, 13 Independent Practice – Book Work