Geometry Section 10-4 1112

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Inscribed Angles

Transcript of Geometry Section 10-4 1112

Section 10-4Inscribed Angles

Thursday, May 17, 2012

Essential Questions

How do you find measures of inscribed angles?

How do you find measures of angles on inscribed polygons?

Thursday, May 17, 2012

Vocabulary

1. Inscribed Angle:

2. Intercepted Arc:

Thursday, May 17, 2012

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

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

Theorems

10.6 - Inscribed Angle Theorem:

10.7 - Two Inscribed Angles:

10.8 - Inscribed Angles and Diameters:

Thursday, May 17, 2012

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

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

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

Example 1

Find each measure.

a. m∠YXW

b. m XZ

Thursday, May 17, 2012

Example 1

Find each measure.

a. m∠YXW

m∠YXW =

12

mYW

b. m XZ

Thursday, May 17, 2012

Example 1

Find each measure.

a. m∠YXW

m∠YXW =

12

mYW =

12

(86)

b. m XZ

Thursday, May 17, 2012

Example 1

Find each measure.

a. m∠YXW

m∠YXW =

12

mYW =

12

(86) = 43°

b. m XZ

Thursday, May 17, 2012

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

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

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

Example 2

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

Thursday, May 17, 2012

Example 2

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

12x −13=9x +2

Thursday, May 17, 2012

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

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

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

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

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

Example 3

Prove the following.

Given: LO ≅ MN

Prove: MNP ≅LOP

Thursday, May 17, 2012

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

Example 4

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

Thursday, May 17, 2012

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

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

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

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

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

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

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

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

Check Your Understanding

p. 713 #1-10

Thursday, May 17, 2012

Problem Set

Thursday, May 17, 2012

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