Enjoy any 5 free lessons!
You can pick. No account needed.
Watch VideoYou have remaining on your free trial.
4 Free Lessons Left
Get unlimited access to all videos and lesson plans with a membership.
So you can keep watching more great videos in class, ask your teacher or principal to get a School plan membership.
Become a member to get full access to our entire library of learning videos, reading material, quiz games, simple DIY activities & more.
Become a member to get full access to our entire library of learning videos, quiz games, & more.
Plans & Pricingto watch this full video.
Access All Videos
and Lessons, No Limits.
Access All Videos
No credit card required,
takes 7 sec to signup.
No card required
Readytogo lessons
that save you time.
Readytogo lessons
If you are on a school computer or network, ask your tech person to whitelist these URLs:
*.wistia.com, fast.wistia.com, fast.wistia.net, embedwistiaa.akamaihd.net
Sometimes a simple refresh solves this issue. If you need further help, contact us.
Create a free account to unlock all content!
Get Full AccessAngle Relationships in Triangles and Transversals
 Show lesson plan & teacher guide
 Show answers to discussion questions
 Show video only
 Allow visiting of other pages
 Hide assessments
What you will learn from this videoWhat you will learn
 The relationship between the angles in a triangle.
 The relationship between the angles formed by a transversal crossing parallel lines.
 That we can use this knowledge to make artwork, build bridges, and even learn about marine life.

Discussion Questions
Before Video
What is an angle?ANSWERAn angle is formed when two rays, lines, or line segments meet.
I can measure angles using a protractor. The unit given is degrees.
A full circle shows 360°. A half circle shows 180°. A quarter circle shows 90°.
The sum of the measures of the new angles is equal to the measure of the original angle.
Answers will vary. Encourage students to hypothesize.
After Video
What are supplementary angles? How can you use supplementary angles to solve problems?ANSWERSupplementary angles have measures that sum to 180°. If I know one angle in a supplementary angle pair, I can subtract it from 180 to find the measure of the missing angle.
The measures of the angles in a triangle add to 180°.
When two lines intersect, vertical angles are opposite each other. Vertical angles are congruent, so they have equal measure.
A transversal is a line that intersects a pair of parallel lines.
Corresponding angles are in the same position on both intersections; they are congruent. Interior angles are both on the inside of the parallel lines; they are supplementary. Exterior angles are both on the outside of the parallel lines; they are supplementary. Alternate angles are across from each other on different lines; alternate exterior and alternate interior angles are congruent.

Vocabulary
 Angle DEFINE
An angle is formed by the intersection of two rays, lines, or line segments.
 Degree DEFINE
The unit used to measure angles.
 Supplementary DEFINE
Angles that add to 180°
 Vertical Angles DEFINE
When two lines intersect, they form 4 angles. Vertical angles are opposite each other in the intersection.
 Parallel Lines DEFINE
Line that, when continued infinitely, never cross.
 Transversal DEFINE
A line that crosses a pair of parallel lines.
 Corresponding Angles DEFINE
Angles that are in the same position on both intersections of a transversal with two parallel lines.
 Interior Angles DEFINE
Angles that are both on the inside of the parallel lines, formed by the transversal.
 Exterior Angles DEFINE
Angles that are both on the outside of the parallel lines, formed by the transversal.
 Alternate Angles DEFINE
Angles that are across from each other on different lines, where they intersect with the transversal.
 Angle DEFINE

Reading Material

Practice Word Problems

Practice Number Problems

Lesson Plan

Teacher Guide