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# Angles - PowerPoint PPT Presentation

Angles. By Mr. Bales. Objective. By the end of this lesson, you will be able to identify, describe, and classify angles.

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Presentation Transcript

### Angles

By Mr. Bales

• By the end of this lesson, you will be able to identify, describe, and classify angles.

• Standard 4MG3.5 - Students need to know the definitions of a right angle, an acute angle, and an obtuse angle. Understand that 90°, 180°, 270°, and 360° are associated respectively, with 1/4, 1/2, 3/4, and full turns.

• How many degrees does it take to go in a complete circle? Or make one full turn?

• Let’s watch a little NBA to find out!!

• NBA

• So, how many degrees are there in a full turn?

• The Babylonians in about 2400 B.C. lived in Mesopotamia, now southern Iraq. They used a number system based on 60. Some believe they divided the circle into 360 degrees because 6 x 60 = 360 degrees. Others believed that they watched the planets and the sun. They knew it took 360 days for the sun’s path to complete a total circuit. Either way, that is how we got the 360 degree circle.

• MJ’s teacher (that’s me) assigned ten problems for homework. MJ started his homework at 4:00 p.m. He completed it at 4:15 p.m. How far has the minute hand turned?

More on Turns

1/2 turn

¼ turn

90°

180°

full turn

¾ turn

360°

• Let’s get on our feet and practice this!!

• Please stand and face the board, which is 12:00.

• Turn 1/4 turn.

• What angle measure is that?

• Turn 1/2 turn.

• What angle measure is that?

• Turn 3/4 turn.

• What angle measure is that?

• Turn a full turn.

• What angle measure is that?

How would you label this Daniella?

B

C

What are Angles?

• Anglesare figures that are formed by two rays or two line segments with a common endpoint.

• You label angles with a < symbol and you place the vertex in the middle of the three points.

Perfect! < ABC or < CBA

Always label angles with vertex in the middle!

Can you label this correctly?

T

U

Right Angles

• There are all kinds of different angles.

• A right angle has a “square corner”.

• An acute angle measures greater than 0º and less than 90º.

• An obtuse angle measures greater than 90º, but less than 180º.

• Let’s hear from Mr. Hardesty as he explains a few different angles.

• Mr. Hardesty!!

### Bales Bucks!!!

• Page 400 - #’s 8 - 19

• Get them all correct, No Math Homework