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3. 1. Reasoning How can you check your results in Problem 3?
   2. ∠ ADB angle  and ∠ BDC angle  are a linear pair. m ∠ ADB = 3 x + 14 m angle  and m ∠ BDC = 5 x − 2 . m angle  What are m ∠ ADB m angle  and m ∠ BDC ? m angle

Problem 4 Using an Angle Bisector to Find Angle Measures

Multiple Choice A C → eh c vector  bisects ∠ DAB . angle  If m ∠ DAC = 58 bold italic m angle  , what is m ∠ DAB ? bold italic m angle

1. 29
2. 58
3. 87
4. 116

	Draw a diagram.
m ∠ CAB = m ∠ DAC Definition of angle bisector   = 58 Substitute. m ∠ DAB = m ∠ CAB + m ∠ DAC Angle Addition Postulate   = 58 + 58 Substitute.   = 116 Simplify. table with 5 rows and 3 columns , row1 column 1 , m angle

The measure of ∠ DAB angle  is 116. The correct choice is D.

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4. K M → k m vector  bisects ∠ JKL . angle  If m ∠ JKL = 72 , m angle  what is m ∠ JKM ? m angle

✓ Lesson Check

Do you know HOW?

Name a pair of the following types of angle pairs.

1. vertical angles
2. complementary angles
3. linear pair
4. P B → p b vector  bisects ∠ RPT angle  so that m ∠ RPB = x + 2 m angle  and m ∠ TPB = 2 x − 6 . m angle  What is m ∠ RPT ? m angle

Do you UNDERSTAND?

5. Vocabulary How does the term linear pair describe how the angle pair looks?

   

6. Error Analysis Your friend calculated the value of x below. What is her error?