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10.3 Inscribed Angles
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Definitions
 Inscribed Angle- is an angle whose vertex is on a
circle and whose sides contain chords of the circle.
 Intercepted Arc- The arc that lies in the interior of an
inscribed angle and has endpoints on the angle.
Measure of an Inscribed Angle Theorem
 If an angle is inscribed in a circle, then its measure is
half the measure of its intercepted arc.
http://ceemrr.com/Geometry2/Arc_Measure/Arc_Measure_print.html
Theorem 10.9
 If two inscribed angles of a circle intercept the same
arc, then the angles are congruent.
Definitions/Terms
If all of the vertices of a polygon lie on a circle, the
polygon is INSCRIBED in the circle and the circle is
CIRCUMSCRIBED about the polygon.
http://www.mathplanet.com/education/geometry/circles/inscribed-angles-and-polygons
Theorem 10.10
 If a right triangle is inscribed in a circle, then the
hypotenuse is a diameter of the circle. Conversely, if
one side of an inscribed triangle is a diameter of the
circle, then the triangle is a right triangle and the
angle opposite the diameter is the right angle.
Theorem 10.11
 A quadrilateral can be inscribed in a circle if and only
if its opposite angles are supplementary.
X, Z, Y, and W lie on some circle,
If and only if m∠X + m∠Y =180°
And m∠W+ m∠Z =180°
Homework
 Pg 616-617 (3-13 odd, 15-23 ODD)