1. Warm-Up
Set-up the proportion and solve for the missing
measurement.
1.
2.

2. Essential Question
Why do we need to use proportions sometimes
when working with dilations?

3. Angle Pairs
Unit 1, Day 14

4. Common Core GPS
MCC8. G. 5: Use informal arguments to
establish facts about the angle sum and
exterior angle of triangles, about the angles
created when parallel lines are cut by a
transversal, and the angle-angle criterion for
similarity of triangles.

5. Language of the Standards
Alternate Interior Angles: pairs of angles formed when a
third line (a transversal) crosses two other lines. These
angles are on opposite sides of the transversal and are
in between the other two lines. When the two other
lines are parallel, the alternate interior angles are
equal.
Linear Pair: adjacent, supplementary angles. A linear
pair forms a straight line.
Same-side Interior angles: pairs of angles formed when
a third line (a transversal) crosses two other lines.
These angles are on the same side of the transversal
and are between the other two lines. When the two
other lines are parallel, same-side interior angles are
supplementary.

6. Same-side Exterior Angles: pairs of angles
formed when a third line (a transversal)
crosses two other lines. These angles are on
the same side of the transversal and are
outside the other two lines. When the two
other lines are parallel, same-side exterior
angles are supplementary.
Transversal: a line that crosses two or more
lines.

7. Alternate Exterior Angles: pairs of angles formed
when a third line (a transversal) crosses two other
lines. These angles are on opposite sides of the
transversal and are outside the other two lines.
When the two other lines are parallel, the alternate
interior angles are equal.
Corresponding Angles: “cut and paste” angles, pairs
of angles formed when the parallel lines are “cut” in
the middle and the angles are placed on top of one
another. These angles have congruent
measurements.
Adjacent Angles: angles are beside each other.
They share a vertex and a ray.

8. Vertical Angles: Angles that are across from
each other when you have two intersecting
lines. They have congruent measurements.

9. Make a list
Let’s make a list of the angles that are congruent
in measurement and those that are
supplementary.
Now let’s discuss their measurements.

10. Angle Pairs and Measurements

11. Solving for x.

12. Solve for y.

13. Solve for y.
How many degrees is angle 2?
2

14. Solve for y.
How many degrees is angle 4?
2

15. Work Session:
_____1] angle 1 is adjacent with what angle?
_____2] angle 6 is same-side interior with what angle?
_____3] angle 1 is corresponding with what angle?
_____4] angle 4 is alternate interior with what angle?
_____5] angle 7 is vertical to what angle?
_____6] angle 8 is alternate exterior to what angle?
_____7] angle 2 is a same side exterior angle with what angle?

18. Closing…
What did you learn from this task? Did you help
with any of the transformations?