1. Table of Contents 28. Inscribed Angles

2. 10.3 Inscribed angles
Standard – MM2G3 – Understand properties of circles
Essential Question – What are the properties of inscribed angles?

3. Definitions
Inscribed angle- an angle whose vertex is on a circle and whose sides are chords of the circle.
Intercepted arc- the arc that the inscribed angle makes B
BCD  ( BD A  C D

4. Formula
The measure of an inscribed  is ½ the measure of its intercepted arc.
mBAC= ½ m BC B A C (

5. Example A
mABD = ?
98o
196o C B D

6. Example x = ? 70 = ½ 7x Or 7x = 140 B 70o A x=20 C ( m AD = ? 7xo 140o

7. Example
Find m Y W
55o Y X C Z

8. Ex: find x. P PQ is a diameter,  R is a rt. . 3x = 900 x = 30 3xo RC Q

9. Quadrilaterals in a circle
If a quadrilateral is inscribed in a circle, the opposite s are supplementary. A
mA + mC = 180o
mB +mD = 180o D B C

10. Ex: x=? and y=?
85 + x = 180
x = 95
80 + y = 180
y = 100 yo xo
85o
80o

11. Assignment
Pg. 616: 9-21 odd, odd

12. Assessment 321 Name 3 properties of inscribed angles
Name 2 rules about inscribed polygons
Name 1 question you have about this material