LESSON A: DEFINING CIRCLES & THEIR PARTS 6/8/2015Geometry/McConaughy1.
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Transcript of LESSON A: DEFINING CIRCLES & THEIR PARTS 6/8/2015Geometry/McConaughy1.
LESSON A: DEFINING CIRCLES
& THEIR PARTS04/18/23 Geometry/McConaughy 1
In this lesson, you will define circles and their
parts.
04/18/23 Geometry/McConaughy 2
VOCABULARYCircle- in a plane, the set of all points that are a given distance (radius) from a common point (center)
04/18/23 Geometry/McConaughy 3
a segment from the center of a circle to a point on the circle
VOCABULARY
Circles are named by their centers.
O
RADIUS
radius -______________________________________________________________________
O: OExample
04/18/23 Geometry/McConaughy 4
Concentric circles- two or more circles which share the same center
VOCABULARY
Congruent circles- two circles which have radii of the same length
3 in. 3 in.
04/18/23 Geometry/McConaughy 5
VOCABULARY CHORD -
____________________________________
DIAMETER -____________________________________
NOTE: Radii, chords, and diametersare all segments in a circle.
segment in a circle with endpoints on the circle
chord which intersects a circle’s center
04/18/23 Geometry/McConaughy 6
VOCABULARY
TANGENT
SECANT
TANGENT -____________________________________
__________________
line which intersects a circle in exactly one point
Point of Tangency
SECANT -____________________________________
__________________
line which intersects a circle in exactly two points
NOTE: Tangents and secants are lines of a circle .
04/18/23 Geometry/McConaughy 7
VOCABULARY CENTRAL ANGLE -
____________________________________
__________________ __________________
INSCRIBED ANGLE -____________________________________
__________________ __________________
__________________
an angle with all points on the circle and legs (sides) two chords of the circle
angle with its vertex at the center and its legs (sides) two radii of the circle
NOTE: Central angles and inscribedangles are angles of a circle.
04/18/23 Geometry/McConaughy 8
An arc of a circle is two points on a circle and the continuous (unbroken)
part of the circle between the two points.
Arc04/18/23 Geometry/McConaughy 9
Classifying Arcs: SEMICIRCLE -
____________________________________
__________________ __________________
MINOR ARC -____________________________________
MAJOR ARC -____________________________________
an arc of a circle whose endpoints are the endpoints of a diameter
arc smaller than a semicircle
arc larger than a semicircle
NOTE: Semicircles, major arcs, andminor arcs are arcs of a circle.
Name five minor arcs.
Name two semicircles.
Name two major arcs.
04/18/23 Geometry/McConaughy 10
SEGMENTSIN CIRCLES
LINES INCIRCLES
ANGLES INCIRCLES
ARCS IN CIRCLES
FINAL CHECKS FOR UNDERSTANDING:
Name the following circles parts, then distinguish among/between those in each category:
radius
diameter
chord
tangent
secant
central angle
inscribed
angle
semicircleminor arc
major arc
Always use correct symbols for segments,lines, angles, and arcs when naming circle parts.
04/18/23 Geometry/McConaughy 11
Homework:
Circle Parts WS
04/18/23 Geometry/McConaughy 12