A postulates list of circles in geometry involves working with things like tangent lines. Learn about a postulates list of circles in geometry with help from an experienced educator in this free video clip.

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A postulates list of circles in geometry involves working with things like tangent lines. Learn about a postulates list of circles in geometry with help from an experienced educator in this free video clip.

Part of the Video Series: Lessons in Math

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Hi, my name is Marija. I'm a mathematician, and today I'm going to give you a list of circle postulates in math. So let's start with a circle, give it a center. Now if you have an exterior point on the circle and we're going to draw a tangent line to the circle. So as best as I can without a ruler I'm going to identify the point of the line that's tangent to the circle and now we're going to draw another line that's tangent to the circle from that same point. The postulate will tell you that if you draw two tangents from the same point that is exterior of the circle, the line segments that you've created, although mine don't look it, the line segments that you created are congruent. So that's the first postulate for you to learn. The two line segments that are created by two tangents that are equally distant from the circle are going to be congruent, that's number one. Now inside of the circle if I draw a couple of cords and I'm going to make these cords parallel so we're assuming that these cords are parallel. Then what we know is that the arcs of the cords that have intersected are also congruent. So that's another postulate about circles, arcs that the parallel cords intersect are going to be congruent. So out of the many postulates and theorems about circles, those are a few. My name is Marija, and I just gave you a short list of postulates on circles.