Notes on 10-3

1. Arcs and Chords
Section 10-3 3108.4.40
Jim Smith
JCHS

2. If 2 chords in a circle are congruent, then the arcs they cut
are also congruent.
Equal chords in a circle are equidistant from the center.
A
B
C
D
AB = CD
A
B
C
D

3. Chords increase in length as they get closer to the center, becoming the
longest chords, diameters, when they pass through the center of the circle.
.
If 2 chords in the same circle are not equal, then
the one closest to the center is the longest.

4. If a diameter or part of a diameter is perpendicular to
a chord, then it bisects the chord and the arc the chord cuts.
.

5. .
If we add a radius, we get a right triangle

6. y² + 9.2² = 10.3²
y² =21.45
Y = 4.6
X = 10.3 – 4.6
X = 5.7
y
x² + 6.4² = 17²
x² = 248.0
X = 15.7 x
x² +3.6² = 10.6²
x² = 99.4
X = 10.0
y
y² + 12.3² = 15.6²
y² = 92.0
Y = 9.6
X = 15.6 – 9.6
X = 6

7. Explain how to use today’s lesson to find the center of this circle.
Draw 2 chords
Find the perpendicular bisector
of each chord
The intersection of the ┴ bisectors
is the center of the circle