Question Video: Understanding Straight Lines Mathematics • 4th Grade

In the figure, which of the following would represent the straight line passing through 𝐵 and 𝐶?

02:59

Video Transcript

In the given figure, which of the following would represent the straight line passing through 𝐵 and 𝐶?

The given figure that our question mentions is this diagram here. We can see that it’s made up of four points labeled 𝐴, 𝐵, 𝐶, and 𝐷. And these are connected together by two paths. We’ve got a line segment that connects 𝐴 and 𝐵, and we’ve got another path that seems to start at 𝐵, pass through 𝐶 and also 𝐷.

Our question asks us how we would represent the straight line that passes through points 𝐵 and 𝐶. But before we look at our possible answers, let’s think about what this question means because at the moment we can’t see a straight line that passes through points 𝐵 and 𝐶. In maths, a line is something very definite. It’s a straight path that continues in both directions and doesn’t end. If we look at our diagram, we can see that we do have an endpoint.

At the moment, the path that goes through points 𝐵 and 𝐶 starts at point 𝐵. It does pass through 𝐶. And we can see by the arrowhead that it does continue on and on, but only in one direction. If we’re looking for the straight line that passes through 𝐵 and 𝐶, we’re looking for something that continues in both directions.

Now, it’s still there, even though it’s not drawn on the diagram. Let’s use our pink pen to show how this line is going to continue. It’s going to carry on past 𝐵 on and on. That’s better. Now, we can imagine what a straight line that passes through both 𝐵 and 𝐶 would look like. But how would we represent this?

Underneath the diagram, we can see five possible answers. We can work out which one’s correct because we know that a straight line continues in both directions. Two of our possible answers have a short line above them with an arrowhead at one end. These are mini versions of rays, not straight lines. We know this because a ray starts from an endpoint and then just continues in one direction. That’s why there’s one arrowhead. The last answer doesn’t have any arrowheads. This represents a line segment, in other words, part of a line between two endpoints. The correct answer of course is this one here.

The symbol at the top is a mini version of a line. Of course, it’s continuing in both directions. That’s why there are two arrowheads. And the letters 𝐵 and 𝐶 tell us two points that our straight line passes through. This is the correct symbol that represents a straight line that passes through points 𝐵 and 𝐶. And we’d read it as line 𝐵𝐶.

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