Download Section 12.4: Inscribed Angles Vertex is on the circle. Sides are

Section 12.4: Inscribed Angles
Vertex is on the circle.
Sides are chords.
Activity
1. Make a circle.
2. Draw a central angle.
3. Draw an inscribed angle that intercepts the same arc as the central angle.
4. Measure the central angle.
5. Measure the inscribed angle.
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Conclusion
The measure of an inscribed angle is equal to half the measure of its intercepted arc.
Example:
Find ADB, BDC, ADC
Find B.
Activity
1. Draw a circle.
2. Draw 2 inscribed angles that intercept the same arc.
3. Measure both angles.
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Conclusion
If two inscribed angles intercept the same arc or congruent arcs, then the angles are congruent.
Activity
1. Draw a circle.
2. Draw a quadrilateral inscribed in the circle.
3. Measure the angles.
4. Compare the opposite angles.
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Conclusion
If a quadrilateral is inscribed in a circle, then its opposite angles are supplementary.
Given: LMN = 113
Find: L, N, and P
Homework
p. 684­685
#1­6, 8, 10­15, 16, 18, 24