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Find the missing alternate angles in these geometry problems.

Worksheet with six problems showing parallel lines and transversals, each with some angles labeled and others to be calculated as alternate angles.

Worksheet with six problems showing parallel lines and transversals, each with some angles labeled and others to be calculated as alternate angles.

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Show Answer Key & Explanations Step-by-step solution for: Geometry Worksheets | Angles Worksheets
Let's solve each problem step by step using the properties of alternate angles and angles formed by parallel lines and a transversal.

🔍 Key Concepts:


- Alternate interior angles are equal when two parallel lines are cut by a transversal.
- Alternate exterior angles are also equal.
- Supplementary angles (on a straight line) add up to 180°.
- Vertical angles (opposite angles at an intersection) are equal.

We’ll assume that the horizontal lines in each diagram are parallel, as is typical in such problems unless stated otherwise.

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Let’s go through each question:

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1)


Given:
- ∠2 = 123.8°
- ∠3 = 56.2°

We need to find ∠1 and ∠4.

#### Step-by-step:
- ∠3 and ∠1 are alternate interior angles → So ∠1 = ∠3 = 56.2°
- ∠2 and ∠4 are alternate interior angles → So ∠4 = ∠2 = 123.8°

Answer:
- ∠1 = 56.2°
- ∠2 = 123.8°
- ∠3 = 56.2°
- ∠4 = 123.8°

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2)


Given:
- ∠3 = 123°
- ∠4 = 56.1°

Find ∠1 and ∠2.

#### Step-by-step:
- ∠3 and ∠1 are alternate interior angles → ∠1 = ∠3 = 123°
- ∠4 and ∠2 are alternate interior angles → ∠2 = ∠4 = 56.1°

Answer:
- ∠1 = 123°
- ∠2 = 56.1°
- ∠3 = 123°
- ∠4 = 56.1°

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3)


Given:
- ∠1 = 123.3°
- ∠2 = 56.7°

Find ∠3 and ∠4.

#### Step-by-step:
- ∠1 and ∠3 are alternate interior angles → ∠3 = ∠1 = 123.3°
- ∠2 and ∠4 are alternate interior angles → ∠4 = ∠2 = 56.7°

Answer:
- ∠1 = 123.3°
- ∠2 = 56.7°
- ∠3 = 123.3°
- ∠4 = 56.7°

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4)


Given:
- ∠2 = 75.2°
- ∠3 = 104.8°

Find ∠1 and ∠4.

#### Step-by-step:
- ∠2 and ∠4 are alternate interior angles → ∠4 = ∠2 = 75.2°
- ∠3 and ∠1 are alternate interior angles → ∠1 = ∠3 = 104.8°

Answer:
- ∠1 = 104.8°
- ∠2 = 75.2°
- ∠3 = 104.8°
- ∠4 = 75.2°

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5)


Given:
- ∠1 = 74.6°
- ∠4 = 106.4°

Find ∠2 and ∠3.

#### Step-by-step:
- ∠1 and ∠3 are alternate interior angles → ∠3 = ∠1 = 74.6°
- ∠4 and ∠2 are alternate interior angles → ∠2 = ∠4 = 106.4°

Answer:
- ∠1 = 74.6°
- ∠2 = 106.4°
- ∠3 = 74.6°
- ∠4 = 106.4°

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6)


Given:
- ∠1 = 45.2°
- ∠2 = 134.8°

Find ∠3 and ∠4.

#### Step-by-step:
- ∠1 and ∠3 are alternate interior angles → ∠3 = ∠1 = 45.2°
- ∠2 and ∠4 are alternate interior angles → ∠4 = ∠2 = 134.8°

Answer:
- ∠1 = 45.2°
- ∠2 = 134.8°
- ∠3 = 45.2°
- ∠4 = 134.8°

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Final Answers Summary:



| Problem | ∠1 | ∠2 | ∠3 | ∠4 |
|--------|----------|----------|----------|----------|
| 1 | 56.2° | 123.8° | 56.2° | 123.8° |
| 2 | 123° | 56.1° | 123° | 56.1° |
| 3 | 123.3° | 56.7° | 123.3° | 56.7° |
| 4 | 104.8° | 75.2° | 104.8° | 75.2° |
| 5 | 74.6° | 106.4° | 74.6° | 106.4° |
| 6 | 45.2° | 134.8° | 45.2° | 134.8° |

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📌 Explanation Recap:


- Alternate angles are equal when two parallel lines are cut by a transversal.
- In all cases, we used the alternate interior angle rule: angles on opposite sides of the transversal but inside the parallel lines are equal.
- The labeling shows that ∠1 and ∠3 are alternate, and ∠2 and ∠4 are alternate.

All answers are consistent with this rule.

Let me know if you'd like a visual explanation or printed version!
Parent Tip: Review the logic above to help your child master the concept of angle practice worksheet.
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