1. Draw 4 concentric circles

2. Draw a circle with r = 4 and center A.

3. What is the diameter of the circle?

4. Explain the difference between a secant & a chord5. What do you know about a tangent line and the radius drawn to the point of tangency?

Session 29

Math II

UNIT QUESTION: What special properties are found with the parts of a circle?Standard: MM2G1, MM2G2

Today’s Question:How do we use angle measures to find measures of arcs?Standard: MM2G3.a,d

P

A

BC

Central Angle : An Angle whose vertex is at the center of the

circleMinor ArcMajor Arc

Less than 180°

More than 180°

ABACB

To name: use 2 letters

To name: use 3 letters

APB is a Central Angle

P

E

F

D

Semicircle: An Arc that equals 180°

EDF

To name: use 3 letters

THINGS TO KNOW AND REMEMBER ALWAYS

A circle has 360 degrees

A semicircle has 180 degrees

Vertical Angles are Equal

measure of an arc = measure of central angle

A

B

C

Q 96

m AB

m ACB

m AE

E

=

=

=

96°

264°

84°

Arc Addition PostulateA

B

C

m ABC =

m AB + m BC

Tell me the measure of the following arcs.

80100

40

140A

B

C

D

R

m DAB =

m BCA =

240

260

Congruent Arcs have the same measure and MUST come from the same circle or of congruent circles.

4545

A

BC

D

110

Classwork

•Workbook Page 204 #12-24

• Homework:

TEXT Book: page 193 #9-23

page 201 #1-10