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Secants, Tangents, and Angle Measures

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Section 10-6Secants, Tangents, and Angle Measures

Monday, May 21, 2012

Essential Questions

How do you find measures of angles formed by lines intersecting on or inside a circle?

How do you find measure of angles formed by lines intersecting outside the circle?

Monday, May 21, 2012

Vocabulary & Theorems

1. Secant:

Theorem 10.12 - Two Secants:

Monday, May 21, 2012

A line that intersects a circle in exactly two points

Vocabulary & Theorems

1. Secant:

Theorem 10.12 - Two Secants:

Monday, May 21, 2012

A line that intersects a circle in exactly two points

Vocabulary & Theorems

1. Secant:

Theorem 10.12 - Two Secants: If two secants or chords intersect in the interior of a circle, then the measure of an angle formed is half of the sum of the measure of the arcs intercepted by the angle and its vertical angle

Monday, May 21, 2012

Vocabulary & Theorems

Theorem 10.13 - Secant and Tangent:

Monday, May 21, 2012

Vocabulary & Theorems

Theorem 10.13 - Secant and Tangent: If a secant and a tangent intersect at the point of tangency, then the measure of each angle formed is half of the measure of its intercepted arc

Monday, May 21, 2012

Vocabulary & Theorems

Theorem 10.14 - Exterior Intersection:

Monday, May 21, 2012

Vocabulary & Theorems

Theorem 10.14 - Exterior Intersection: If two secants, a secant and a tangent, or two tangents intersect in the exterior of a circle, then the measure of the angle formed is half the difference of the measures of the intercepted arcs

Monday, May 21, 2012

Example 1

Find x. a.

Monday, May 21, 2012

Example 1

Find x. a.

m∠FDE = 180 − m∠EDH

Monday, May 21, 2012

Example 1

Find x. a.

m∠FDE = 180 − m∠EDH

m∠EDH =76 + 882

Monday, May 21, 2012

Example 1

Find x. a.

m∠FDE = 180 − m∠EDH

m∠EDH =76 + 882

=1642

Monday, May 21, 2012

Example 1

Find x. a.

m∠FDE = 180 − m∠EDH

m∠EDH =76 + 882

=1642

= 82°

Monday, May 21, 2012

Example 1

Find x. a.

m∠FDE = 180 − m∠EDH

m∠EDH =76 + 882

=1642

= 82°

m∠FDE = 180 − 82

Monday, May 21, 2012

Example 1

Find x. a.

m∠FDE = 180 − m∠EDH

m∠EDH =76 + 882

=1642

= 82°

m∠FDE = 180 − 82 = 98°

Monday, May 21, 2012

Example 1

Find x. a.

m∠FDE = 180 − m∠EDH

m∠EDH =76 + 882

=1642

= 82°

m∠FDE = 180 − 82 = 98°

x = 98Monday, May 21, 2012

Example 1

Find x. b.

Monday, May 21, 2012

Example 1

Find x. b.

x = 180 − m∠VZW

Monday, May 21, 2012

Example 1

Find x. b.

x = 180 − m∠VZW

m∠VZW =96 + 622

Monday, May 21, 2012

Example 1

Find x. b.

x = 180 − m∠VZW

m∠VZW =96 + 622

=1582

Monday, May 21, 2012

Example 1

Find x. b.

x = 180 − m∠VZW

m∠VZW =96 + 622

=1582

= 79°

Monday, May 21, 2012

Example 1

Find x. b.

x = 180 − m∠VZW

m∠VZW =96 + 622

=1582

= 79°

x = 180 − 79

Monday, May 21, 2012

Example 1

Find x. b.

x = 180 − m∠VZW

m∠VZW =96 + 622

=1582

= 79°

x = 180 − 79 = 101

Monday, May 21, 2012

Example 1

Find x. c.

Monday, May 21, 2012

Example 1

Find x. c.

60 = x + 252

Monday, May 21, 2012

Example 1

Find x. c.

60 = x + 252

120 = x + 25

Monday, May 21, 2012

Example 1

Find x. c.

60 = x + 252

120 = x + 25

x = 95

Monday, May 21, 2012

Example 2

Find each measure.

a. m∠QPS when mPTS = 250°

Monday, May 21, 2012

Example 2

Find each measure.

a. m∠QPS when mPTS = 250°

m∠QPS = 1

2mPTS

Monday, May 21, 2012

Example 2

Find each measure.

a. m∠QPS when mPTS = 250°

m∠QPS = 1

2mPTS

=12(250)

Monday, May 21, 2012

Example 2

Find each measure.

a. m∠QPS when mPTS = 250°

m∠QPS = 1

2mPTS

=12(250) = 125°

Monday, May 21, 2012

Example 2

Find each measure.

b. mBD

Monday, May 21, 2012

Example 2

Find each measure.

b. mBD

mBD = 360 − 2m∠ADB

Monday, May 21, 2012

Example 2

Find each measure.

b. mBD

mBD = 360 − 2m∠ADB= 360 − 2(108)

Monday, May 21, 2012

Example 2

Find each measure.

b. mBD

mBD = 360 − 2m∠ADB= 360 − 2(108)

= 360 − 216

Monday, May 21, 2012

Example 2

Find each measure.

b. mBD

mBD = 360 − 2m∠ADB= 360 − 2(108)

= 360 − 216

= 144°

Monday, May 21, 2012

Example 3

a. mBC when m∠AED = 62°

Find each measure.

Monday, May 21, 2012

Example 3

a. mBC when m∠AED = 62°

Find each measure.

m∠AED =

mABD − mBC

2

Monday, May 21, 2012

Example 3

a. mBC when m∠AED = 62°

Find each measure.

m∠AED =

mABD − mBC

2

62 = 141− x2

Monday, May 21, 2012

Example 3

a. mBC when m∠AED = 62°

Find each measure.

m∠AED =

mABD − mBC

2

62 = 141− x2

124 = 141− x

Monday, May 21, 2012

Example 3

a. mBC when m∠AED = 62°

Find each measure.

m∠AED =

mABD − mBC

2

62 = 141− x2

124 = 141− x

−17 = −x

Monday, May 21, 2012

Example 3

a. mBC when m∠AED = 62°

Find each measure.

m∠AED =

mABD − mBC

2

62 = 141− x2

124 = 141− x

−17 = −xx = 17

Monday, May 21, 2012

Example 3

a. mBC when m∠AED = 62°

Find each measure.

m∠AED =

mABD − mBC

2

62 = 141− x2

124 = 141− x

−17 = −xx = 17 mBC = 17°

Monday, May 21, 2012

Example 3

b. mXYZFind each measure.

Monday, May 21, 2012

Example 3

b. mXYZFind each measure.

m∠W =

mXYZ − mXZ

2

Monday, May 21, 2012

Example 3

b. mXYZFind each measure.

m∠W =

mXYZ − mXZ

2

40 = mXYZ −140

2

Monday, May 21, 2012

Example 3

b. mXYZFind each measure.

m∠W =

mXYZ − mXZ

2

40 = mXYZ −140

2

80 = mXYZ −140

Monday, May 21, 2012

Example 3

b. mXYZFind each measure.

m∠W =

mXYZ − mXZ

2

40 = mXYZ −140

2

80 = mXYZ −140

mXYZ = 220°Monday, May 21, 2012

Check Your Understanding

p. 731 #1-7

Monday, May 21, 2012

Problem Set

Monday, May 21, 2012

Problem Set

p. 732 #9-29 odd, 41, 47

"I hate quotations. Tell me what you know."– Ralph Waldo Emerson

Monday, May 21, 2012

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