Welcome to class

The warm up is

1-2 Word puzzle on the table

Let’s grade your homework

1.3 Measuring Angles

Please get:

♥one piece of patty paper

♥protractor

♥your notes

With the straight edge, draw these angles on your patty paper (DO NOT FREE HAND):

S R

P

Q

Measure each angle.

Do you notice anything?

Angle Addition Postulate

m PQS + m SQR = m PQR

P

Q

S

R

Which one makes sense?

A + B = 85°

Or

m A + m B = 85°AB

Angle Congruence Postulate

♥ If two angles have the same measure, then they are congruent.

♥ the converse is also true:

If two angles are congruent, then they have the same measure.

• COMPLEMENTARY Angles – Exactly two angles whose sum is 90°. Each angle is a COMPLEMENT of the other.

• SUPPLEMENTARY Angles = Exactly two angles whose measure is 180°. Each angle is a SUPPLEMENT of the other.

A 60° 120°

C

30°

B

Complementary angles are A and B

A and B are complements of each other

A and C are supplementary angles

A and C are supplements of each other

Are you

doing

ok?

Linear Pair Property

If two angles form a line, they are a linear pair AND are supplementary.

125° 55°

Angles

RIGHT ANGLE = 90°INDICATED BY THE BOX IN THE CORNER

ACUTE ANGLE = angle less than 90°OBTUSE ANGLE = angle more than 90° but less

than 180°STRAIGHT ANGLE = angle that equals 180°REFLEX ANGLE = angle greater than 180° and

less than 360°.

Whiteboards

Please get a whiteboard, marker,

and eraser.

Doodle time starts in one minute.

Your assignment

1.3 Wksht