Geometric constructions congruent segments
About this video
The video shows how to construct a line segment congruent to a given one using only a compass and a straight edge. The compass is set to the length of the original segment, then an arc is drawn from a new endpoint, and any point on that arc can be the other endpoint.
You'll be able to
- use a compass to copy the length of a line segment.
- construct a congruent segment with a compass and straight edge.
- explain why any point on the arc gives a segment of the same length.
Key words
- congruent segments
- Line segments that have exactly the same length.
- compass
- A tool with two points that keeps a fixed distance, used to draw circles and arcs.
- straight edge
- A tool like a ruler used only to draw straight lines, not to measure.
- endpoint
- A point at either end of a line segment.
Transcript
- [Instructor] What we're gonna do in this video is learn how to make congruent line segments using just a compass, I have one here. And a straight edge, like a ruler. So there's a bunch of ways you could do this, but first, let's just make a line segment here.
So right over there, I'm just drawing that arbitrarily. And now let me use my straight edge to actually connect the points. So there we go, I have my line segment. Now there's a bunch of ways I could do it. Let's say I want this to be the end point of my new line segment that is congruent.
It might be in a different orientation. One option is I could take this ruler and I could try to measure it out and get the same distance over here. But instead what I'm gonna do is just use my compass. So if I just take my compass and make it so that one point is at one end point and that the other point is right over at the other end point, just like that.
So there you go. Then I could do the same thing over here, put one endpoint there, and now any point that's on this other edge here could be the endpoint of a congruent line segment. So I could just pick that arbitrarily and then take my straight edge here. Sorry, this camera, I'm just using it the first time.
It's going in and out of focus, but hopefully you can see what's going on. And there you have it. I've just made a congruent line segment, same length, different orientation.
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