Lines and Angles

Terra Alta/East Preston School

Geometry Unit

Ray

Ray--part of a line that has one endpoint and goes on endlessly in the other direction.

Congruent

Equal in size and shape.

Degrees

The unit used to measure angles.

70

Line Segment

A part of a line that has two endpoints.

Line

A series of points that goendlessly in both directions.

Vertex

The point at which two rays join together to form an angle.

Obtuse Angle

An angle that measures morethan 90 degrees.

Acute Angle

An angle that measuresless than 90 degrees.

Right Angle

An angle that measures90 degrees.

Straight Angle

An angle that measures180 degrees. (a.k.a. straightline)

Parallel Lines

Two lines that are equaldistance apart and willnever intersect.

Perpendicular Lines

Two lines that intersect toform two right angles.

Complimentary Angles

Two angles thatadd up to 90 degrees.

Supplementary Angles

Two angles thatadd up to 180 degrees.

*****Reminders******

SupplementaryStraight angleComplimentaryCorner

***Reminders****

means angle

B R

D E F

Q S

BEF DER QRS DEF BER

CIRCLESRadius: a line segment whoseendpoints are thecenter of a circleand a point on thecircle.

Diameter

A line segmentthat passes

through the center of acircle and has endpointson the circle.

Arc

ABA

B

Part of a circle

The End