1. Arcs
Chapter 9
Section-4
Chords

2. Theorem 9-4: In the same circle or in congruent circles…
(1) Congruent arcs have congruent chords.
(2) Congruent chords have congruent arcs.
Why is this true? A B D C E

3. Theorem 9-5: A diameter that is perpendicular to a chord
bisects the chord and its arc. A B O C D Z
Why is this true? 2 1
Point O is the center

4. Theorem 9-6: In the same circle or in congruent circles…
Theorem 9-6: In the same circle or in congruent circles…
(1) Chords equally distant from the center are congruent.
(2) Congruent chords are equally distant from the center. A B C O D

5. Find the values of x and y .
Find the values of x and y . #1 #2 O E F x 6 y O x y 5 13 .

6. #3 What does x & AB equal?
#4 What’s B B D C 8 O O x
220º A A C

7. Sketch a circle O with radius 17mm and a chord 30mm long How far is the chord from O? O 15 15 x
172 = x2
8 = x 17

8. :9-4 Arcs & Chords: Homework
Homework:
Section 9.4 Written Exercises (p. 347) #1-13 (all) & (all)
9.3 & 9.4 Practice worksheet