# Geometry Circles

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1. What is a circle?
The set of points that are equidistant from a given point. It is not a polygon because it does no have sides.
The distance from the center of the circle a point on the circle. All radii are congruent in a circle.
3. What is a chord?
A segment whose endpoints are on a circle.
4. What is a diameter?
A chord that passes through the center of the circle. It is the longest chord in a circle.
5. What is a secant line?
A line that intersects a segment in two points. It goes on through the circle.
6. What is a tangent?
A line that intersects the circle in exactly one point.
7. What are tangent circles?
Circles that intersect at one point.
8. What are concentric circles?
Circles with no point of intersection and share the same intersection.
9. What is a common tangent?
A tangent that touches two circles. There can be between 0 and 4 common tangents between circles. Try to draw a picture for a situation of each.
The tangent line is perpindicular to the radius that touches the point of tangency.
11. What do you know about tangents to a circle that intersect (Party Hat Theorem).
The tangents are congruent to each other.
12. What do you know about central angles?
They are angles with their vertices on the center of the circle. They form arcs that have the same measure as the central angle.
13. What is a minor arc?
An arc that is less than 180o. A minor arc has only two points in notation.
14. What is a major arc?
An arc with more than 180o. It is notated with three points and you must figure it out by going around the circle.
15. What is a semicircle?
An arc whose endpoints are on a diameter and it is 180o.
16. What makes congruent circles?
17. What makes congruent arcs?
Arcs of the same measure that are on the same circle or are on two congruent circles.
18. What do you know about about the measures of two minor arcs if the chords that make them are congruent?
The arcs are congruent.
19. What do you know about a diameter that is perpendicular to a chord?
The diameter bisects the chord and the arc that the chord makes.
20. What do you know about chords that are equidistant from the center of a circle?
The chords are congruent.
21. What is an inscribed angle?
An angle with its vertex on the circle and the sides contain chords of the circle.
22. What is an intercepted arc?
The arc on the interior of an inscribed angle.
23. What is an inscribed angle?
It is half of the arc that it makes.
24. What do you know about inscribed angles that share the same arc?
They are congruent.