Lines and Angles

Learning Target I can… Name and classify angles

Angles Two rays that share the same endpoint form an angle. The point where the rays intersect is called the vertex of the angle. The two rays are called the sides of the angle.

We can specify an angle by using a point on each ray and the vertex. The angle below may be specified as angle ABC or as angle CBA; you may also see this written as ABC or as CBA. Note how the vertex point is always given in the middle.

Naming Angles 1) 2)

Which angles are the same measure?

Which angle measures 90˚?

Types of Angles Acute – Obtuse – Right – Straight –

1. A. 90 ˚ B. 120 ˚ C. 46 ˚ D. 180 ˚ A. Acute B. Obtuse C. Right D. Straight

2. A. Acute B. Obtuse C. Right D. Straight A. 90 ˚ B. 110 ˚ C. 49 ˚ D. 180 ˚

3. A. Acute B. Obtuse C. Right D. Straight A. 90 ˚ B. 110 ˚ C. 40 ˚ D. 85 ˚

4. A. Acute B. Obtuse C. Right D. Straight A. 92 ˚ B. 100 ˚ C. 165 ˚ D. 85 ˚

Using a Protractor

Center Mark Zero Edge Outer Scale Inner Scale

Step 2: Line up angle vertex at this point. Step 3: Line up zero edge Step 1: Ask yourself, acute or obtuse? Step 4: Read your angle measure

What is the measure of ECA shown below? C E A

What is the measure of angle FCS shown below? C F S

What is the measure of angle CAB shown below? C B A R

What is the measure of angle TRE shown below? E T R W Z

Two angles are Adjacent if they have a common side and a common vertex (corner point)angles Adjacent Angles

Name Pairs of Adjacent Angles _______ and _______

Angle CBD is 54°. What angle is adjacent to angle CBD?

Angle EBC is 58°. What angle is adjacent to angle EBC?

EXIT Estimate the measure of angle x. A. 10 ° B. 63° C. 95° D. 126°

Now, use a protractor on the same angles… 1.

Continued… 2.

Again… 3.

Next One… 4.

How close was your estimate?

Learning Target: I can… Identify complementary and supplementary angles

Review from yesterday…. 4 Types of Angles? Naming Angles? Measuring Angles?

Angles Supplementary: Complementary:

Are these angles complementary or supplementary? What is the measure of the missing angle? a.Supplementary, 18° b.Complementary, 18° c.Supplementary, 108° d.Complementary, 108° 72°

Are these angles complementary or supplementary? What is the measure of the missing angle? a.Supplementary, 75° b.Complementary, 75° c.Supplementary, 165° d.Complementary, 165° x 15˚

m GJC = 77˚ m LJC = ?

What is the measure of angle B? a.90° b.68° c.22° d.112° 112°B

60˚ B What is the measure of angle B?

Review from Yesterday Supplementary Angles *Magic Number = 180˚ *Make a straight line Complementary Angles *Magic Number = 90˚ *Make a right angle

45º C Find the measure of angle C. __________

Find the measure of angle B 72° B

The measure of angle COE is 123˚. What is the measure of angle BOC?

Angles of a Triangle The sum of the angles of a triangle is 180 ˚ 89˚ 12˚

Problem of the Day

Isosceles Triangles 2 sides are the same So 2 angles are the same

Find the measure of angle B

You try! Find the measure of angle B 17° 90° B

Stations

Station 1 A right triangle has a 40˚ angle. What is the measure of the third angle? What is the measure of each angle of an equilateral triangle? Station 2 A right triangle has a 40˚ angle. What is the measure of the third angle? What is the measure of each angle of an equilateral triangle? Station 2

Station 1 A right triangle has a 40˚ angle. What is the measure of the third angle? What is the measure of each angle of an equilateral triangle? Station 2 A right triangle has a 40˚ angle. What is the measure of the third angle? What is the measure of each angle of an equilateral triangle? Station 2

Station 3

Station 4

Station 5

Station 6

Station 7

Station 8 Find the measures of the missing angles. (A,B,C)

Learning Target I can… Find missing angles

Exit Find the measure of angle x: a.65° b.50° c.115° d.180° x65° 50°

Learning Target I can… Find missing angles

Exit Find the measure of angle a and b: a 65° 50° b

Exit If angle y = 48˚, what is angle x?

Learning Target I can… Ace my quiz!

Exit: Name a pair of complementary angles