**Group 3 1-1 CE**

Circle

A closed plane curved all points which are equidistant from a point within called the CENTER.

Circumference

Length of a cirlce.

Radius

Chord

A line segment joining any two points on the circle.

Diameter

Secant and Secant Segment

Secant lines touches exactly 2 different points

Secant segment is a part of secant line but has its endpoint outside the circle

Tangent

Tangent lines are lines that touches exactly one point called point of tangency

Tangent segment is a part of a tangent line between the point of tangency and an point outside the circle

Common Tangent

is a line that is tangent to each of two coplanar circles. Example: CD and FD

Common Internal Tangent

is a common tangent that intersects the segment joining the centers of two circles. Example: FD

Common External Tangent

is a common tangent that does not intersect the segment joining the centers of two circles. Example: CD

Segment ( Segment of centers)

– is the segment whose endpoints are the center of two circles

Central angle

- is an angle formed by two radii, so its vertex is the center of the circle and the radii are the sides.

Inscribed Angle

- is an angle whose vertex is a point on the circle and whose sides are chords. A central angle is a inscribed angle but its vertex is on the middle that is why it has a different name. A inscribed angle should have it’s vertex inside the circle otherwise it may not be called an Inscribed Angle.

Arc

- any portion of the circumference of the circle.

Classifications of Arc:

Semicircle

- an arc equal to half of a cirlce (180˚)

Minor Arc

- an arc less than semicircle (1˚-179˚)

Major Arc

- an arc greater than semicircle (181˚-359˚)

*arcs can be measured in usual

linear units or in arc degrees

Arc Degree

- measure of an arc intercepted on a circle by the sides of a central angle of 1˚

Intercepted Arc

- an arc formed when segments intersect portions of a circle.

Sector of a circle

- the figure bounded by 2 radii and the intercepted arc; region enclosed by the central angle of a circle and the circle itself.

Segment of a circle

- figure bounded by an arc and its chord

Circumscribed Polygon

- a polygon circumscribed about a circle, with each side of which tangent to a circle. The circle is said to be inscribed in the polygon. The center of this circle is called incenter of a polygon

Inscribed polygon

- a polygon inscribed in a circle, with each side of which is a chord of the circle. The circle is said to be circumscribed about the polygon. The center of the circle is called the circumcenter of the polygon

center of a regular polygon

is also the center of the circumscribed and inscribed circle

radius of a regular polygon

is the radius of the circumscribed circle

apothem of a regular polygon

is the radius of the inscribed circle

central angle of a regular polygon

is an angle formed at the center by any two adjacent vertices of the polygon

congruent or equal circles

are two circles whose radii are equal or congruent

concentric circles

are two or more circles with a common center but their not equal

intersecting circles

are circles that intersect at two distinct points

tangent circles

are two circles that are tangent on the same line at the same point

Internally tangent

circles are two circles whose centers are on the same side of a tangent line

Externally tangent

circles are two circles whose centers are on the opposite sides of a tangent line

Projection of a point upon a line is the foot of the perpendicular from the point to the line.

The projection of a point on a line when it is external to the line i.e. a point not belonging to the line is "A point that represents the foot of the perpendicular drawn from the point to the line".

Projection of a line segment upon a line is the locus of the projections of all the points of the segment upon the line.

Locus of a point is the path which contains all the points and only those which satisfy certain given geometric conditions.

The locus of points at a given distance from a given point is a circle whose center is the given point and whose radius is the given distance.

Ratio

of two quantities is the quotient obtained by dividing one number by another

Three ways to write Ratios:

Word notation = A is to B

Odds notation = A : B

Fractional notation = A/B

Proportion

is the equality of two ratios. Each of the four quantities of a proportion is a term. The first and the fourth are the extremes; the second and the third are the means

Mean proportion

is a proportion in which the second and third terms are equal.

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

A chord passing through the center of the circle. It is also the longest chord that can be drawn on a circle.

Sources

http://math.tutorvista.com/geometry/secant-of-a-circle.html

http://mathtestpreparation.com/lessons/GeoLesson12.aspx

Solid Geometry by Clarita R. Guevara, http://quizlet.com/10057417/print, http://www.sparknotes.com/math/geometry1/circles/section2.rhtml

, http://www.mathwarehouse.com/geometry/circle/arc-of-circle.php, http://www.sparknotes.com/math/geometry1/circles/section2.rhtm

http://www.basic-mathematics.com

http://img.sparknotes.com

www.chegg.com, www.schoolingkids.com