2. inscribed angle An angle whose vertex is on the circle and
whose sides contain chords of the circle.
The measure of an inscribed angle is ½ the
measure of its intercepted arc.
•
H
A
I
R
∠ =
1
m AHR AR
2
= ⋅ ∠AR 2 m AHR
3. Example Find each measure:
1. m∠MAP
2.
M
A
P
110º
J
Y
O
24º24º24º24º
mJY
4. Example Find each measure:
1. m∠MAP
2.
= 2(24)
= 48º
M
A
P
110º
J
Y
O
24º24º24º24º
mJY
( )∠ =
1
m MAP mMP
2
= = °
1
(110) 55
2
= ∠mJY 2(m JOY)
5. If inscribed angles intercept the same arc,
then the angles are congruent.
R
E
A D
∠RED ≅ ∠RAD
6. An inscribed angle intercepts a semicircle if
and only if it is a right angle.
•
7. If a quadrilateral is inscribed in a circle, its
opposite angles are supplementary.
F
R
E
D
FRED is inscribed
in the circle.
m∠F + m∠E = 180º
m∠R + m∠D = 180º