Geometry Circle Definitions And Theorems

Front 1

Circle

Back 1

Set of points in a plane that are a given distance from a given point.

Front 2

Center

Back 2

The given point in a circle from which every point is equidistant

Front 3

Radius

Back 3

A segment extending from the center to any point on the circle.

Front 4

Chord

Back 4

A segment that joins two points on the circle

Front 5

Diameter

Back 5

A chord that contains the center of the circle

Front 6

Secant

Back 6

A line, ray, or segment that contains a chord

Front 7

Congruent circles

Back 7

Circles with congruent radii

Front 8

Concentric circles

Back 8

Two or more coplanar circles having the same center

Front 9

Sphere

Back 9

Set of all points in a space that are a given distance from a given point

Front 10

Tangent line

Back 10

Lies in the plane of the circle and intersects the circle in exactly one point, called the point of tangency

Front 11

Theorum: If a line is tangent to a circle, then the line is _________________ to the circle at the point of tangency

Back 11

Perpendicular

Front 12

Corollary 1 Two tangent segments from a common external point are __________

Back 12

Congruent

Front 13

Theorem: If a line in the plane of a circle is perpendicular to a radius at its endpoint on the circle, then the line is ___________ to the circle

Back 13

Tangent

Front 14

Theorem: In the same circle, or in congruent circles, two minor arcs are congruent if and only if __________________

Back 14

Their central angles are congruent

Front 15

Theorem: In the same circle, or in congruent circles, two minor arcs are congruent if and only if _________________

Back 15

Their chords are congruent

Front 16

Theorem: If a diameter is perpendicular to a chord, then it ____________

Back 16

Bisects the chord and its arc