The document discusses arc measures in circles. It defines central angle, minor arc, major arc, and semicircle. It explains that the measure of a minor arc is equal to the measure of its central angle and the measure of a major arc is 360 degrees minus the minor arc. The document also presents the arc addition postulate and notes that congruent arcs have the same measure if they are in congruent circles.

1. 10.2 Arc Measures
HW pg. 661 #4­17
February 27, 2015
Give the name that best describes FD.
Chord
2. Is AB tangent to C? Explain.
3. Find x.
Yes; 162 + 302 = 1156 = 342
12
Bellwork

2. 10.2 Arc Measures
HW pg. 661 #4­17
February 27, 2015
10.2 Arc Measures
Central Angle: angle's vertex is the center of circle
Minor Arc: arc less than 180
Major Arc: points not on the minor arc
Semicircle: arc with endpoints of diameter
C
A
B
C B
A
D
C B
A
C
AD
minor arc AB
major arc ADB
<ACB
Measure of minor arc = measure of central <
C
A
B
50 mAB=50
Measure of major arc = 360 ‐ minor arc
C
A
B
50
D
mADB = 360 ­ 50= 310
Semicircle AD

3. 10.2 Arc Measures
HW pg. 661 #4­17
February 27, 2015

4. 10.2 Arc Measures
HW pg. 661 #4­17
February 27, 2015
Arc Addtion Postulate
D
C B
A
mABD = mAB + mBD

5. 10.2 Arc Measures
HW pg. 661 #4­17
February 27, 2015
Congruent Circles: same radius
Congruent Arcs: same measure in congruent circles

6. 10.2 Arc Measures
HW pg. 661 #4­17
February 27, 2015
HW pg. 661 #4‐17