7-6 Circles & Arcs7-7 Area of Circles and Sectors

Vocabulary

A

G

E

B

C D

F

Circle A or A

Radius AB, AE, AF

Diameter BE

Chord CD, BE

Vocabulary

Circle = 360

Arc: BGE, EF, FB, FBG

Minor Arc (less than 180 ) BF, FE, EG, GB

Major Arc (more than 180)

FBG, FBE, GEB

Semicircle (equals 180)

BGE, BFE

A

G

E

B

F

Vocabulary

Central Angle – angle whose vertex is the center of the circle

<BAF, <FAE

A

G

E

B

F

Vocabulary & Formulas

Concentric Circles – circles that have same center.

Circumference – distance around circle

C = 2r or C = d

Area A =r2

H

JI

K

Length of an Arc: what’s the formula?

75

FormulasMeasure of an

arc is always in degrees

measure of arc = central angle

Arc Length is always in dimensions

2 r360

mL

Area of Sector: What is the formula?

75

Formula

360

mArea of a Sector

A = r2

Formula

Area of a segment

Segment

1) Find area of Sector2) Find area of Triangle3) Area of Segment = area of

sector minus area of triangle

Examples5) Find mFG

6) Find mIJH

7) Find mFIG

8) IF JG=5cm, find the

length of GFI

8050

FG

I

H

Examples

1) If KJ = 5 find the area of circle K.

2) If = 120 and

KL = 6, what is the area of sector JKL?

3) If m<JKL = 135 and

KJ = 2, what is the area of sector JKL?

mJL K

J

L

Examples: Find area of segment.

O B

A

8

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