Basic Geometry Concepts
Types of Angles
Types of Triangles
Pairs of Lines
Pairs of Angles
100

Connects to endpoints.

line segment

100

An angle that is less than 90 degrees.

Acute angle 

100

The triangle has three equal sides

equilateral

100

Lines that never intersect.

parallel lines

100

Two angles measurements equal 90 degrees.

complementary angles

200

An exact location in space.

Point

200

An angle that is exactly 90 degrees.

right angle

200

This triangle has two equal sides.

isosceles 

200

lines that intersect at one point and form a 90 degree angle.

perpendicular lines

200

two angles measurements that equal 180 degrees

supplementary angles

300

A set of points that lie on the same.

collinear 

300

An angle that is exactly 180 degrees.

Straight angle

300

This triangle has no equal sides

scalene

300

Lines that meet at a point.

Intersecting lines

300

Two pairs of angles that are formed by intersecting lines.  The angles are equal to each other.  They are also opposite angles.

Vertical angles

400

All points and lines that lie on the plane.

coplanar

400

An angle that is greater than 90 degrees, but less than 180 degrees.

obtuse angle

400

This triangle has three angles less than 90 degrees.

acute triangle

400

These lines never intersect, because they are not on the same plane.

skew lines

400

Two angle that share a common side and vertex.  The angles are next to each other.

adjacent angles

500

An _________ is formed when two rays share an endpoint.

angle

500

An angle that is greater than 180 degrees, but less than 360 degrees.

Reflex angle

500

This triangle has one angle greater than 90 degrees.

Obtuse triangle

500

Compare/contrast parallel lines and skew lines.

parallel lines are two coplanar lines that never intersect

skew lines are lines that are not coplanar and can never intersect

500

The line that intersects two parallel lines.

transversal line

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