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### Course: Geometry (all content)>Unit 2

Lesson 8: Sal's old angle videos

# Angles formed between transversals and parallel lines

Angles of parallel lines. Created by Sal Khan.

## Want to join the conversation?

• So transversals only apply to a line that intersects two parallel lines? I'm confused because in my textbook it says 'A line that intersects two other coplanar lines is called a transversal'. :-/ Could somebody help me out? Thanks a lot!
• There is no requirement that a transversal intersect only parallel lines. The intersected lines may or may not be parallel.

The properties you learn are what happens when a transversal happens to intersect parallel lines.
• How many degrees is in an obtuse angle??
• An obtuse angle is an angle that is greater than 90°; yet, it's less than 180°.
• I am asking a question that relates to the video but isn't exactly covered. When there are 2 parallel lines being transversed by 2 other parallel lines where are the alternate interior/exterior angles of any given angle? That is to say, there are 4 lines (2 sets of parallels) intersecting each other. Pick one angle and identify the alternate interior angles, then identify the alternate exterior angles. Any help with this question or a link to another video would be greatly appreciated. Thanks!
• How can one identify corresponding angles in between a transversal and two parallel lines?
• The vertex was formed as the 2 parallel lines were being intersected by the transversal that was meeting the lines at points called vertex. And this is how a vertex is formed.
• why is the sum of angles of a triangle 180?
• Because there's a theorem behind it and to know that you have to research about maths : )
• what are Alternate Interior Angles?
• Alternate Interior Angles are angles inside the parallel lines on opposite sides of a transversal
• Okay. I have a problem with one given angle measure, and two variables (x) that I believe are corresponding. There are two transversals going through. How do I solve for that?
• At he says green instead of yellow.
• Does The transversal need to be one single line when intersecting 3 or more lines or can it be like 2 lines as 1 line per pair of pair of parallel lines??
(1 vote)
• I see no reason why a transversal line can't cut through more than 2 lines.

A set of lines can have any amount of transversals, but the angles formed when when say "transversal x" intersect say lines "a" and "b", have no necessary relation to the angles from the intersection of transversal y and a and b.

In other words, a set of lines can have any positive amount of transversals, but the angles resulting from a transversal have no necessary relation to any other transversal line's angles.

Also, transversals don't have to intersect parallel lines; they could go through perpendicular or non-special intersecting lines, as long as the transversal intersects them both.

I hope this helps!