lesson 8-1: circle terminology 1 lesson 8-1 circle terminology
TRANSCRIPT
Lesson 8-1: Circle Terminology 1
Lesson 8-1
Circle Terminology
Lesson 8-1: Circle Terminology 2
Circle DefinitionCircle : The set of points coplanar points equidistant from a
given point.
The given point is called the CENTER of the circle.
The distance from the center to the circle is called the RADIUS.
Center
Radius
Lesson 8-1: Circle Terminology 3
DefinitionsChord : The segment whose endpoints lie on the circle.
Chord
Diameter : A chord that contains the center of the circle.
DiameterSecant : A line that contains a chord.Secant
Tangent : A line in the plane of the circle that intersects the circle in exactly one point.
Point of Tangency :
The point where the tangent line intersects the circle.
Tangent
Lesson 8-1: Circle Terminology 4
Example: In the following figure identify the chords, radii, and diameters.
, ,AB BF CEChords:
Radii:
Diameter:
O
D
A
B
F
C
EFB
Lesson 8-1: Circle Terminology 5
Circles that have congruent radii.
22
Circles that lie in the same plane and have the same center.
Definitions
Concentric circles :
Congruent Circles :
Lesson 8-1: Circle Terminology 6
Polygons
A polygon inside the circle whose vertices lie on the circle.
Inscribed Polygon:
Circumscribed Polygon :
A polygon whose sides are tangent to a circle.
Lesson 8-1: Circle Terminology 7
ARCSThe part or portion on the circle from some point B to C
is called an arc.
A
B
CBC
Arcs :
Semicircle: An arc that is equal to 180°.
Example:
OA
B
CExample: ABC
Lesson 8-1: Circle Terminology 8
Minor Arc & Major Arc
AB
Minor Arc : A minor arc is an arc that is less than 180°
A minor arc is named using its endpoints with an “arc” above.
A
B
Example:
Major Arc: A major arc is an arc that is greater than 180°.
A major arc is named using its endpoints along with another point on the arc (in order).A
B
CExample: ABC
O
Lesson 8-1: Circle Terminology 9
Example: ARCSIdentify a minor arc, a major arc, and a semicircle, given that
is a diameter. , , ,DE EC CF DF
A
C
D
E
F
Minor Arc:
CD
Major Arc: , , ,CEF EDC DFE FCD
Semicircle: , , ,CED CFD EDF ECF