Geometry Flashcards
A point
has no size and is the simplest geometric figure.
All geometric figures consist of
points
A line
is understood to be a straight line that extends in both directions without end.
A plane
can be thought of as a floor or a tabletop, except that a plane extends in all directions without end and has no thickness.
Given any two points on a line, a line segment is
the part of the line that contains the two points and all the points between them.
Given any two points on a line, a line segment is the part of the line that contains the two points and all the points between them. The two points are called
endpoints
congruent line segments
Line segments that have equal lengths
midpoint
The point that divides a line segment into two congruent line segments
line segments BC and CD are
congruent
point c is
halfway between B and D, point C is the midpoint of line segment BD.
Sometimes the notation AB denotes line segment AB, and sometimes it denotes the
length of line segment AB
When two lines intersect at a point, they form
four angles
When two lines intersect at a point, they form four angles. Each angle has
a vertex at the point of intersection of the two lines.
APC and BPD, are called
opposite angles, also known as vertical angles
Opposite angles have
equal measures
congruent angles
angles that have equal measures
Sometimes the angle symbol is used instead of the word
angle
perpendicular lines
Two lines that intersect to form four congruent angles
Two lines that intersect to form four congruent angles are called perpendicular lines. Each of the four angles has a measure of
90º
An angle with a measure of 90º is called a
right angle
this means
perpendicular
acute angle
An angle with measure less than 90º
obtuse angle
an angle with measure between 90º and 180º
parallel lines
Two lines in the same plane that do not intersect
