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# Geometric constructions: perpendicular bisector

CCSS.Math:

## Video transcript

we're asked to construct a perpendicular bisector of the line segment a B so the fact this perpendicular means that this line will make a 90 degree angle where it intersects with a B it's going to bisect it so it's going to go halfway in between and I have at my disposal some tools I can put out I can draw things with a compass and I can add a straightedge so let's try this out so let me add a compass and so this is kind of a virtual compass or in a real compass it's one of those little metal things where you can pivot it on one point and you can draw a circle of any radius and so here I'm going to draw I'm going to Center it at a I'm going to Center it at a I'm going to make the radius equal to the length of a B now I'm going to add another circle with my compass and now I'm going to Center it at B and make the radius equal to equal to a B and now this gives me two points that I can actually use to draw my perpendicular bisector if I connect at this point and this point it is going to bisect a B and it's also going to be perpendicular so let's add a straightedge here so this is to draw a line so I'm going to draw a line between that point and that point right over there let me scroll down so you can look at a little bit clearer so there you go that's my construction I've made a perpendicular bisector for segment a B check my answer we got it right