Line
is straight (no curves), has no thickness, and. extends in both directions without end (infinitely)
Line Segment
Part of a line between two endpoints
Ray
A straight line that extends from a point
Plane
Is a flat, two-dimensional surface that extends infinitely far. two-dimensional analogue of a point (zero dimensions), a line (one dimension) and three-dimensional space.
Parallel Lines
Two or more straight lines that do not intersect
Skew Lines
Straight lines that are neither parallel, nor intersecting. They lie in different places
Perpendicular Lines
Two lines that intersect at right angles
Angle
The union of two segments with a common end point
Vertex
The endpoint of two sides of a triangle that make up an angle
Right Angle
An angle that measures 90 degrees. It is the angle between two perpendicular lines such as the corner of a square
Acute Angle
An angle with a measure between 0 degrees and 90 degrees
Obtuse Angle
An angle that is between 90 degrees and 180 degrees
Straight Angle
An angle whose measure is 180 degrees
Reflex Angle
An angle that is between 180 degrees and 360 degrees
Adjacent Angles
Two angles that share the same vertex and have one side in common between them
Vertical Angles
The pair of angles opposite each other formed by two intersecting lines
Complementary Angles
If the sum of the measures of two angles is 90 degrees, each angle is said to be the complement of the other angle
Supplementary Angles
Two angles that add up to 180 degrees
Corresponding Angles
Formed when a transversal passes through two lines. The angles that are in the same position in terms of transversals are called corresponding angles
Alternate Interior Angles
Either pair of interior angles lying on opposite sides of the transversal, which are formed when a transversal cuts two lines
Alternate Exterior Angles
Defined as two exterior angles on opposite sides of a transversal which lie on different parallel lines
Consecutive Interior Angles
Defined as two interior angles lying on the same side of the transversal cutting across two parallel lines
Dihedral Angles
The angle between two plans, where each plane is defined by three atoms
Quadrilateral
A polygon with 4 sides and the sum of all angles equals 360
Square
figure with four equal straight sides and four right angles
Rectangle
A four-sided plane figure formed by two pairs of parallel lines that cross each other at right angles
Parallelogram
A four-sided polygon with both pairs of opposite sides parallel
Kite
two non overlapping pair of adjacent sides
Rhombus
A four-sided plane figure whose four sides are equal
Trapezoid
Exactly one pair of parallel sides
Isosceles Trapezoid
One pair of parallel sides, the opposite pair is congruent
Base Angles
Either of the angles of a triangle that have one side in common with the base
Triangle
A closed plane figure with three straight sides.
The sum of the three interior angles in a triangle is always 180�.
Isosceles Triangle
A triangle in which at least two sides are congruent.
Equilateral Triangle
A triangle that has all three sides congruent
Equiangular
A triangle that has all three interior angles congruent
Scalene Triangle
A triangle having no two sides equal
Right Triangle
A triangle one of whose interior angles is 90 degrees
Hypotenuse
The longest side opposite the right angle in a right triangle
Legs (in a right triangle)
In a right triangle, a leg is either of the two sides that form the right angle
Acute Triangle
A triangle in which all three interior angles are acute (less than 90 degrees)
Obtuse Triangle
A triangle that has an obtuse angle (greater than 90 degrees) in its interior
Point
A point specifies only location; it has no length, width, or depth. We usually represent a point with a dot on paper