GEOMETRY: LINES
WARM UP
1.What is the sum of the angles of a triangle?
2.(𝒙𝟓 )(-3𝒙−𝟔 )
3.Tell whether the equation has one solution, no
solutions, or infinitely many solutions:
9k + 1 = 4k – 1 + 5k
4. 0.𝟑 x
𝟏
2
𝟑
QUICK WRITE
Take a few minutes to write down all the
things you know/remember about angles
and geometry. Use the correct
vocabulary and give examples where you
can. Be ready to share your ideas with
your partner and then the class.
Today you will work in pairs to discover the
relationships between angles that are formed
when a set of parallel lines is cut by a transversal.
You will need a piece of paper, a pencil, ruler, and
a protractor to help you with this task.
Step one:
Draw a set of parallel lines.
Step two:
Using your ruler, draw a transversal – a line that
goes through both of the parallel lines.
Step three: The top angle on the left should be named 1, the
top angle on the right should be named 2, and so
forth. It should look like the example below.
1 2
3 4
5 6
7 8
Step four:
Measure each of the angles 1 through 8.
Step five:
Record your angles in a table like the one below.
Angle
Measure in
degrees
Angle
1
5
2
6
3
7
4
8
Step six:
Measure in
degrees
Answer the questions on the next slide.
1.Which angles are congruent?
2.Which angles are supplementary?
3.Can you name pairs of supplementary angles that
are not touching?
4.Write down two or three things you noticed whilst
working with your partner on this task.
The terms below are commonly used when describing angles that are formed
when parallel lines are intersected by a transversal.
• supplementary
• exterior
alternate
corresponding
vertical
interior
Use the terms, and what you have observed about angle pairs, to label each
group of angles shown in the table below. Some groups can be described
using more than one term. List any angles that may be missing from each
group.
Group 1
Group 2
Group 3
∠ 𝟑 𝒂𝒏𝒅 ∠𝟓
∠𝟒 𝒂𝒏𝒅 ∠𝟔
∠𝟑 𝒂𝒏𝒅 ∠𝟔
∠𝟒 𝒂𝒏𝒅 ∠𝟓
∠𝟏 𝒂𝒏𝒅 ∠𝟖
∠𝟐 𝒂𝒏𝒅 ∠𝟕
Group 4
Group 5
Group 6
∠𝟑 𝒂𝒏𝒅 ∠𝟕
∠𝟐 𝒂𝒏𝒅 ∠𝟔
∠𝟏 𝒂𝒏𝒅 ∠𝟑
∠𝟔 𝒂𝒏𝒅 ∠𝟖
∠𝟑 𝒂𝒏𝒅 ∠𝟒
∠𝟏 𝒂𝒏𝒅 ∠𝟒
∠𝟐 𝒂𝒏𝒅 ∠𝟑
Now it is time to take some notes. We are going to construct a
FOLDABLE.
Take your handout and fold the top and bottom half of the sheet
along the dotted lines.
Then, carefully cut along the solid lines. You will need to make six
cuts.
Now, if ∠ 𝟏is 65°, find the measures of the other angles. Use
what you have just learned. Give a reason for your answer.
65° 2
3 4
5 6
7 8
1=
2=
3=
4=
5=
6=
TICKET OUT THE DOOR……
Complete the worksheet by answering numbers
one through six.
Then answer…….
HOMEWORK
Use your FOLDABLE to help you with tonight’s homework.