Angle MeasurementAngle Measurement

Lesson 2bLesson 2b

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Definitions:Definitions:

A.A. A ray is the part of a line consisting of one A ray is the part of a line consisting of one endpoint and all the points of the line on endpoint and all the points of the line on one side of the endpoint.one side of the endpoint.

B.B. A ray goes on forever in one direction A ray goes on forever in one direction without ending.without ending.

C.C. A ray is named by first stating the A ray is named by first stating the endpoint and then one other point in the endpoint and then one other point in the direction of the ray.direction of the ray.

D.D. For example, the ray above could be For example, the ray above could be named-- named--

•A B

Ray AB or ABRay AB or AB

I.I. RayRay

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Definitions Definitions Cont.Cont. •B

•C

A

A.A. An angle is formed by two rays with An angle is formed by two rays with the same endpoint.the same endpoint.

B.B. The two rays are called the The two rays are called the sidessides of of the angle.the angle.

C.C. The common endpoint is called the The common endpoint is called the vertexvertex..

II.II. AngleAngle

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Definitions Definitions Cont.Cont. •B

•C

A

When naming an angle:1) The middle letter is always the vertex.2) The first letter is one point on one of the rays.3) The last letter is one point on the other ray.

II.II. AngleAngle cont . . . cont . . .D.D. An angle is named a few different An angle is named a few different

ways: For our purposes we will ways: For our purposes we will most often use three points to most often use three points to name an angle. name an angle.

E.E. For example, the angle above could For example, the angle above could be named: be named: BACBAC..

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Definitions Definitions Cont.Cont. •B

•C

A

A.A. Figures that have the same size & same Figures that have the same size & same shape are shape are congruent ( congruent ( ) )..

B.B. Segments are congruent if they are the Segments are congruent if they are the same length.same length.

C.C. Angles are congruent if they are the same Angles are congruent if they are the same degree measure.degree measure.

III.III. CongruenceCongruence

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D.D. ROC is congruent to ROC is congruent to XYZ.XYZ.This can be written, ROC XYZ.

R••O• C

X•Y• Z•

48º 48º

Angle Measurement:Angle Measurement:

A.A. The symbol for degree is a small The symbol for degree is a small raised zero (°).raised zero (°).

B.B. We use a We use a protractorprotractor to measure to measure angles.angles.

Protractor

40°

I.I. Angles are measured using units called Angles are measured using units called degreesdegrees..

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Angle Measurement Angle Measurement cont…cont…

II.II. Angles can be classified according to Angles can be classified according to their measure.their measure.

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Angles less than 90° are called Acute Angles.

Angles equal to 180° are called Straight Angles.

Angle Measurement Angle Measurement cont…cont…

Acute Angle: Obtuse Angle:

Right Angle: Straight Angle:

Types of Angles:Types of Angles:

Angles greater than 90° are called Obtuse Angles.

Symbol for right angle

180°

Angles equal to 90° are called Right Angles.

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Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

Next

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

Choose the correct measure.

160° 20°orNext

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

That’s Correct!

20°20°20°20°20°20°Next

20°

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

How would you classify this angle?

Next

Click here toreview Angle Types

ObtuseAcute Right Straight

Choose one!

20°

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

That’s Correct!

Acute

Click here toreview Angle Types

Next Angle

20°

Angles less than 90° are called Acute Angles.

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

Next

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

Choose the correct measure.

130° 50°orNext

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

That’s Correct!

130°Next

130°

130°130°130°130°130°

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

Click here toreview Angle Types

How would you classify this angle?

Next

ObtuseAcute Right Straight

Choose one!

130°

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

That’s Correct!

Obtuse

Click here toreview Angle Types

Next Angle

130°

Angles greater than 90° are called Obtuse Angles.

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

Next

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

Choose the correct measure.

118° 60°Next

62° 78°

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

That’s Correct!

62°Next

62°62°62°62°62°

62°

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

How would you classify this angle?

Next Angle

Click here toreview Angle Types

ObtuseAcute Right Straight

Choose one!

62°

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

That’s Correct!

Acute

Click here toreview Angle Types

Next Angle

62°

Angles less than 90° are called Acute Angles.

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

Next

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

Choose the correct measure.

180° 90°Next

0° 110°

90°

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

That’s Correct!

90°Next

90°90°90°90°90°

90°

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

How would you classify this angle?

Next

Click here toreview Angle Types

ObtuseAcute Right Straight

Choose one!

90°

Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

That’s Correct!

Right

Click here toreview Angle Types

Next

Angles equal to 90° are called Right Angles.

Angles less than 90° are called Acute Angles.

Angles equal to 180° are called Straight Angles.

Angles equal to 90° are called Right Angles.

Angle Measurement Angle Measurement cont…cont…

Acute Angle: Obtuse Angle:

Right Angle: Straight Angle:

Types of Angles:Types of Angles:

Angles greater than 90° are called Obtuse Angles.

Symbol for right angle

180°

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Angle Measurement Angle Measurement cont…cont…Click on the protractor to measure each angle, then Click on the protractor to measure each angle, then classify the angle as acute, right, obtuse, or classify the angle as acute, right, obtuse, or straight.straight.

Sorry Try Again!

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