Angles

1
Angles

• Student Expectations
• 6th Grade 6.3.6A
• Use angle measurements to classify angles as
  acute, obtuse, or right.
• 7th Grade 7.3.6A
• Use angle measurements to classify pairs of
  angles as complementary or supplementary.

2
How do you Classify Angles?

• Angles are classified according to their
  measurement. Angles are measured in degrees. The
  symbol stands for degrees. You can write the
  measure of an angle using notation such as m
  T 40. The equation m T 40 is read as
  the measure of angle T equals 40 degrees. 
• If two angles have an equal measure, they are
  congruent. For example, if m R 40 and m
  S 40, then R is congruent to S.

3
Classify Angles
Type Angle Description
Acute ? An acute angle measures more than 0 but less than 90.
Right ? A right angle measures exactly 90. Right angles are formed by perpendicular lines.
Obtuse ?An obtuse angle measures more than 90 but less than 180.
Straight ? A straight angle measures 180. Straight angles are formed by rays that lie on a line.
4
Classify Angle Pairs
Type Angle Pair Description
Complementary ?Two angles are complementary if the sum of their measures is 90.
Supplementary ? Two angles are supplementary if the sum of their measures is 180.
5
What do we use to help us?

• A protractor

Here is a standard protractor like you use in
the classroom.
6
When we use a protractor, we need to line it up
correctly.

• You need to make sure the protractor is lined up
  correctly.
• Is this ready to measure the angle?

7
Were you right......................it wasnt

• Look for the upside down T in the middle of the
  straight line on your protractor.
• This needs to be exactly on the vertex of your
  angle.

8
We need to remember.....
It doesnt matter which way round the angle
is, you ALWAYS need to line the upside down T
to the vertex of the angle.
9
Now you are ready.

• Read from the 0, and follow the inner set of
  numbers.

10
Once you reach 30 you need to be careful!!!

• You then need to look at the 1 markings on the
  outer set of numbers.

11
What does it measure?

• This angle measures 35.