12-2 Notes and answers Reg Geo.notebook -...

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122 Notes and answers Reg Geo.notebook 1 December 04, 2015 Nov 2510:09 PM Apply properties of arcs. Apply properties of chords. Objectives Nov 2510:09 PM A central angle is an angle whose vertex is the center of a circle. An arc is an unbroken part of a circle consisting of two points called the endpoints and all the points on the circle between them.

Transcript of 12-2 Notes and answers Reg Geo.notebook -...

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Apply properties of arcs.

Apply properties of chords.

Objectives

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A central angle is an angle whose vertex is the center of a circle. An arc is an unbroken part of a circle consisting of two points called the endpoints and all the points on the circle between them.

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Minor arcs may be named by two points. Major arcs and semicircles must be named by three points.

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Example 1: Data Application

The circle graph shows the types of grass planted in the yards of one neighborhood. Find mKLF.

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Check It Out! Example 1

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Example 2: Using the Arc Addition Postulate

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Check It Out! Example 2a Find each measure.

     mJKL 

m∠KPL = 180° – (40 + 25)°

= 25° + 115°

mKL = 115°mJKL = mJK  + mKL 

= 140°

Arc Add. Post.

Substitute.

Simplify.

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Check It Out! Example 2b Find each measure.

     mLJN 

= 295°mLJN = 360° – (40 + 25)°

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Example 3A: Applying Congruent Angles, Arcs, and Chords

TV ≅ WS.  Find mWS.

= 88 Simplify.

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Example 3B: Applying Congruent Angles, Arcs, and Chords

8C ≅ 8J, and m∠GCD ≅ m∠NJM. Find NM.

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Check It Out! Example 3a

PT bisects ∠RPS.  Find RT. 

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Check It Out! Example 3b

8A ≅ 8B, and CD ≅ EF.  Find mCD. Find each measure.

25y° = (30y – 20)°20 = 5y4 = yCD = 25(4)mCD = 100°

mCD = mEF

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Find NP.

Example 4: Using Radii and Chords

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QR = 2(17.3) =  PS ^  QR , so PS bisects QR.

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Assignment(p. 797) 9, 10, 12, 26(p. 806) 5­18, 25­32, 38, 39