Draw the following:

Line AB

Line segment BC

Ray FG

Warmup

Section 1.6: Measuring angles

LEQ: How do we classify angles?

An angle is the union of two rays that share a common endpoint.

There are 4 ways to name an angle:

CED DEC E 3

Acute angles have measuresbetween 0 and 90 degrees

Right angleshave measuresof exactly 90degrees

(indicated by a small square)

Obtuse angleshave measuresbetween 90and 180 degrees

Straight Angle – an angle measuring 180 degrees

Right angle

Straight angle

Acute angle

Obtuse angle

Congruent angles are angles of the same measure(indicated by identical markings)

Similar to the ruler postulate, if point B is in the interior of AOC, then mCOB+mBOA=mCOA

(<AOC)

Postulate 1-8: Angle Addition Postulate

Vertical angles are opposite congruent angles created by the intersection of two lines

<1 and <3 are vertical angles <2 and <4 are

vertical angles

Why should m<1=m<3

Adjacent angles are angles that share a common side, common vertex, and no common interior points.

<KIH and <KIJ are adjacent angles

Complementary angles are two angles who’s measures sum to 90.

<TSU and <USV are

complementary angles.

If m<TSU=42, what is m<USV?

<TSU is the complement of

<USV

Supplementary angles are two angles who’s measures sum to 180.

<TSU and <USV are supplementary angles. <TSU is the supplement of<USV. If m<TSU=120, what is m<USV?

Use the adjacent angles below to solve the following:

m<HOK = 4x-6, m <KOB=6x+2, find x andm<HOK.

Ex. 1

Line up the bottom of the protractor with a side of the angle and center of angle with center of protractor. Extend the line of the other side and read the degree.

How do we measure angles?

p.40-41, 1-8,15,17,19,24-32 odds,43,45

Hwk: