Chapter 10.1 - 10.3 Circles Flashcards
Exterior of a circle
Points outside of a circle.
Chord
A segment whose endpoints are on the circle.
Diameter
A chord that passes through the center of a circle.
Radius
A segment whose endpoints consist of the center of the circle and a point on the circle.
Tangent
If a line intersects a circle at exactly one point, then the line is a tangent of the circle.
Secant
If a line intersects a circle at two points, then the line is a secant of the circle.
Common tangent
A line that is tangent to two circles.
Common external tangent
A common tangent that does not intersects the segment that joins the centers of the circle.
Interior of a circle
Points inside of a circle.
Common internal tangent
A common tangent that intersects the segment that joins the centers of the circle.
Two circles can intersect in 4 different ways:
1) two circles can have no points of intersection.
2) two circle can have exactly one point of intersection ( circles are tangent to each other ).
3) two circles can have exactly two points of intersection.
4) two circles can have infinitely many points of intersection.
Concentric circles
Circles that have the same center.
Congruent circles
Circles with congruent radii or diameters.
Theorem 10.1
If a line is tangent to a circle, then it is perpendicular to the radius drown to the point of tangency.
Theorem 10.2
In a plane, if a line is perpendicular to a radius of a circle, at its endpoints on the circle, then the line is tangent to a circle.