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Section 10-4 Inscribed Angles Thursday, May 17, 2012

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Inscribed Angles

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Page 1: Geometry Section 10-4 1112

Section 10-4Inscribed Angles

Thursday, May 17, 2012

Page 2: Geometry Section 10-4 1112

Essential Questions

How do you find measures of inscribed angles?

How do you find measures of angles on inscribed polygons?

Thursday, May 17, 2012

Page 3: Geometry Section 10-4 1112

Vocabulary

1. Inscribed Angle:

2. Intercepted Arc:

Thursday, May 17, 2012

Page 4: Geometry Section 10-4 1112

Vocabulary

1. Inscribed Angle: An angle made of two chords in a circle, so that the vertex is on the edge of the circle

2. Intercepted Arc:

Thursday, May 17, 2012

Page 5: Geometry Section 10-4 1112

Vocabulary

1. Inscribed Angle: An angle made of two chords in a circle, so that the vertex is on the edge of the circle

2. Intercepted Arc: An arc with endpoints on the sides of an inscribed angle and in the interior of the inscribed angle

Thursday, May 17, 2012

Page 6: Geometry Section 10-4 1112

Theorems

10.6 - Inscribed Angle Theorem:

10.7 - Two Inscribed Angles:

10.8 - Inscribed Angles and Diameters:

Thursday, May 17, 2012

Page 7: Geometry Section 10-4 1112

Theorems

10.6 - Inscribed Angle Theorem: If an angle is inscribed in a circle, then the measure of the angle is one half the measure of the intercepted arc

10.7 - Two Inscribed Angles:

10.8 - Inscribed Angles and Diameters:

Thursday, May 17, 2012

Page 8: Geometry Section 10-4 1112

Theorems

10.6 - Inscribed Angle Theorem: If an angle is inscribed in a circle, then the measure of the angle is one half the measure of the intercepted arc

10.7 - Two Inscribed Angles: If two inscribed angles of a circle intercept the same arc or congruent arcs, then the angles are congruent

10.8 - Inscribed Angles and Diameters:

Thursday, May 17, 2012

Page 9: Geometry Section 10-4 1112

Theorems

10.6 - Inscribed Angle Theorem: If an angle is inscribed in a circle, then the measure of the angle is one half the measure of the intercepted arc

10.7 - Two Inscribed Angles: If two inscribed angles of a circle intercept the same arc or congruent arcs, then the angles are congruent

10.8 - Inscribed Angles and Diameters: An inscribed angle of a triangle intercepts a diameter or semicircle IFF the angle is a right angle

Thursday, May 17, 2012

Page 10: Geometry Section 10-4 1112

Example 1

Find each measure.

a. m∠YXW

b. m XZ

Thursday, May 17, 2012

Page 11: Geometry Section 10-4 1112

Example 1

Find each measure.

a. m∠YXW

m∠YXW =

12

mYW

b. m XZ

Thursday, May 17, 2012

Page 12: Geometry Section 10-4 1112

Example 1

Find each measure.

a. m∠YXW

m∠YXW =

12

mYW =

12

(86)

b. m XZ

Thursday, May 17, 2012

Page 13: Geometry Section 10-4 1112

Example 1

Find each measure.

a. m∠YXW

m∠YXW =

12

mYW =

12

(86) = 43°

b. m XZ

Thursday, May 17, 2012

Page 14: Geometry Section 10-4 1112

Example 1

Find each measure.

a. m∠YXW

m∠YXW =

12

mYW =

12

(86) = 43°

b. m XZ

m XZ =2m∠XYZ

Thursday, May 17, 2012

Page 15: Geometry Section 10-4 1112

Example 1

Find each measure.

a. m∠YXW

m∠YXW =

12

mYW =

12

(86) = 43°

b. m XZ

m XZ =2m∠XYZ =2(52)

Thursday, May 17, 2012

Page 16: Geometry Section 10-4 1112

Example 1

Find each measure.

a. m∠YXW

m∠YXW =

12

mYW =

12

(86) = 43°

b. m XZ

m XZ =2m∠XYZ =2(52) =104°

Thursday, May 17, 2012

Page 17: Geometry Section 10-4 1112

Example 2

Find m∠QRT when m∠QRT = (12x − 13)° and m∠QST = (9x + 2)°.

Thursday, May 17, 2012

Page 18: Geometry Section 10-4 1112

Example 2

Find m∠QRT when m∠QRT = (12x − 13)° and m∠QST = (9x + 2)°.

12x −13=9x +2

Thursday, May 17, 2012

Page 19: Geometry Section 10-4 1112

Example 2

Find m∠QRT when m∠QRT = (12x − 13)° and m∠QST = (9x + 2)°.

12x −13=9x +2 3x =15

Thursday, May 17, 2012

Page 20: Geometry Section 10-4 1112

Example 2

Find m∠QRT when m∠QRT = (12x − 13)° and m∠QST = (9x + 2)°.

12x −13=9x +2 3x =15

x =5

Thursday, May 17, 2012

Page 21: Geometry Section 10-4 1112

Example 2

Find m∠QRT when m∠QRT = (12x − 13)° and m∠QST = (9x + 2)°.

12x −13=9x +2 3x =15

x =5

m∠QRT =12(5)−13

Thursday, May 17, 2012

Page 22: Geometry Section 10-4 1112

Example 2

Find m∠QRT when m∠QRT = (12x − 13)° and m∠QST = (9x + 2)°.

12x −13=9x +2 3x =15

x =5

m∠QRT =12(5)−13 =60−13

Thursday, May 17, 2012

Page 23: Geometry Section 10-4 1112

Example 2

Find m∠QRT when m∠QRT = (12x − 13)° and m∠QST = (9x + 2)°.

12x −13=9x +2 3x =15

x =5

m∠QRT =12(5)−13 =60−13 = 47°

Thursday, May 17, 2012

Page 24: Geometry Section 10-4 1112

Example 3

Prove the following.

Given: LO ≅ MN

Prove: MNP ≅LOP

Thursday, May 17, 2012

Page 25: Geometry Section 10-4 1112

Example 3

Prove the following.

Given: LO ≅ MN

Prove: MNP ≅LOP

There are many ways to prove this one. Work through a proof on your own. We will discuss a few in class.

Thursday, May 17, 2012

Page 26: Geometry Section 10-4 1112

Example 4

Find m∠B when m∠A = (x + 4)° and m∠B = (8x - 4)°.

Thursday, May 17, 2012

Page 27: Geometry Section 10-4 1112

Example 4

Find m∠B when m∠A = (x + 4)° and m∠B = (8x - 4)°.

m∠A+m∠B +m∠C =180

Thursday, May 17, 2012

Page 28: Geometry Section 10-4 1112

Example 4

Find m∠B when m∠A = (x + 4)° and m∠B = (8x - 4)°.

m∠A+m∠B +m∠C =180 x +4+8x −4+90=180

Thursday, May 17, 2012

Page 29: Geometry Section 10-4 1112

Example 4

Find m∠B when m∠A = (x + 4)° and m∠B = (8x - 4)°.

m∠A+m∠B +m∠C =180 x +4+8x −4+90=180

9x +90=180

Thursday, May 17, 2012

Page 30: Geometry Section 10-4 1112

Example 4

Find m∠B when m∠A = (x + 4)° and m∠B = (8x - 4)°.

m∠A+m∠B +m∠C =180 x +4+8x −4+90=180

9x +90=180 9x =90

Thursday, May 17, 2012

Page 31: Geometry Section 10-4 1112

Example 4

Find m∠B when m∠A = (x + 4)° and m∠B = (8x - 4)°.

m∠A+m∠B +m∠C =180 x +4+8x −4+90=180

9x +90=180 9x =90 x =10

Thursday, May 17, 2012

Page 32: Geometry Section 10-4 1112

Example 4

Find m∠B when m∠A = (x + 4)° and m∠B = (8x - 4)°.

m∠A+m∠B +m∠C =180 x +4+8x −4+90=180

9x +90=180 9x =90 x =10

m∠B =8(10)−4

Thursday, May 17, 2012

Page 33: Geometry Section 10-4 1112

Example 4

Find m∠B when m∠A = (x + 4)° and m∠B = (8x - 4)°.

m∠A+m∠B +m∠C =180 x +4+8x −4+90=180

9x +90=180 9x =90 x =10

m∠B =8(10)−4 =80−4

Thursday, May 17, 2012

Page 34: Geometry Section 10-4 1112

Example 4

Find m∠B when m∠A = (x + 4)° and m∠B = (8x - 4)°.

m∠A+m∠B +m∠C =180 x +4+8x −4+90=180

9x +90=180 9x =90 x =10

m∠B =8(10)−4 =80−4 =76°

Thursday, May 17, 2012

Page 35: Geometry Section 10-4 1112

Check Your Understanding

p. 713 #1-10

Thursday, May 17, 2012

Page 36: Geometry Section 10-4 1112

Problem Set

Thursday, May 17, 2012

Page 37: Geometry Section 10-4 1112

Problem Set

p. 713 #11-35 odd, 49, 55, 61

“You're alive. Do something. The directive in life, the moral imperative was so uncomplicated. It could be expressed in single words, not

complete sentences. It sounded like this: Look. Listen. Choose. Act.”- Barbara Hall

Thursday, May 17, 2012