Use a protractor to measure angles

An angle measure of 1° (read as “one degree”) means that one side of an angle is rotated ________ of a complete revolution about the vertex from the other side of the angle

The measure of ∠ ABC , shown below, is 1°. We can write this in symbols as m(∠ ABC) = 1°

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• An angle measure of 90° is equivalent to 1($)
• An angle measure of 180° is equivalent to 2($)
• An angle measure of 270° is equivalent to 3($)

•  1($)

•  2($)

•  3($)

• ∠ ABC = 1($)°
• ∠ ABD = 2($)°
• ∠ ABE = 3($)°
• ∠ ABF = 4($)°
• ∠ ABG = 5($)°
• ∠ GBF = 6($)°
• ∠ GBC = 7($)°

• 1($): Angles whose measures are greater than 0° but less than 90°.
• 2($): Angles whose measures are 90°.
• 3($): Angles whose measures are greater than 90° but less than 180°.
• 4($): Angles whose measures are 180°

1($)

2($)

3($)

4($)

Choose the symbol which is commonly drawn in a right angle

Since m(∠1) is an 1($)angle.

Since m(∠2) is an 2($) angle.

Since m(∠BDE) is a 3($) angle.

Since m(∠ABC) is a 4($) angle

• ∠ DEG is 1($) angle
• ∠ DEF is 2($) angle
• ∠ EFG is 3($) angle
• ∠ EGF is 4($) angle
• ∠ GEF is 5($) angle