Estimating Angles Worksheets - Free Printable

To solve the problem of estimating the angles in the given diagrams, we need to analyze each diagram and determine the measure of the angle based on geometric principles. Let's go through each part step by step.

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Part A:

#### Diagram 1:
- The diagram shows a right angle.
- A right angle is defined as an angle measuring exactly 90°.
- Answer: 90°

#### Diagram 2:
- The diagram shows an acute angle.
- An acute angle is an angle that measures less than 90°.
- From the visual estimation, the angle appears to be approximately 45°.
- Answer: 45°

#### Diagram 3:
- The diagram shows an obtuse angle.
- An obtuse angle is an angle that measures more than 90° but less than 180°.
- From the visual estimation, the angle appears to be approximately 135°.
- Answer: 135°

#### Diagram 4:
- The diagram shows a reflex angle.
- A reflex angle is an angle that measures more than 180° but less than 360°.
- From the visual estimation, the angle appears to be approximately 270°.
- Answer: 270°

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Part B:

#### Diagram 1:
- The diagram shows two parallel lines intersected by a transversal.
- The marked angle is an alternate interior angle to the given 60° angle.
- Alternate interior angles are congruent when the lines are parallel.
- Therefore, the marked angle is also 60°.
- Answer: 60°

#### Diagram 2:
- The diagram shows two parallel lines intersected by a transversal.
- The marked angle is a corresponding angle to the given 120° angle.
- Corresponding angles are congruent when the lines are parallel.
- Therefore, the marked angle is also 120°.
- Answer: 120°

#### Diagram 3:
- The diagram shows two parallel lines intersected by a transversal.
- The marked angle is a same-side interior angle to the given 110° angle.
- Same-side interior angles are supplementary (sum to 180°) when the lines are parallel.
- Therefore, the marked angle is 180° - 110° = 70°.
- Answer: 70°

#### Diagram 4:
- The diagram shows two parallel lines intersected by a transversal.
- The marked angle is a vertical angle to the given 80° angle.
- Vertical angles are congruent.
- Therefore, the marked angle is also 80°.
- Answer: 80°

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Final Answers:

- Part A:
1. 90°
2. 45°
3. 135°
4. 270°

- Part B:
1. 60°
2. 120°
3. 70°
4. 80°

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Boxed Final Answer:

\[
\boxed{
\text{Part A: } 90^\circ, 45^\circ, 135^\circ, 270^\circ \\
\text{Part B: } 60^\circ, 120^\circ, 70^\circ, 80^\circ
}
\]