point
an exact location with no size, only position. It is represented as a dot.
line
a straight continuous arrangement of an infinite number of points. It has no width and extends in both directions forever.
collinear points
points located on the same line
plane
a flat surface having infinite length but no width.
compass
a tool used to create arcs and circles
straightedge
a ruler with no numbers
sketch
to free-hand a non-precise geometric figure without using tool
draw
to precisely draw geometric figures by using measuring tools such as protractors and rulers.
construct
to create an exact geometric figure using a compass or straightedge
coplanar lines
lines that are located on the same plane.
skew lines
lines that are not on the same plane and never intersect.
ray
a part of a line that begins with a single point and extends indefinitely in one direction
endpoint of a ray
single point where the ray begins
line segement
a part of a line that includes two points and all the collinear points in between
endpoints of a line segment
the points where the line segment begins and ends
congruent line segments
two or more line segments of equal measure
Distance formula
a formula for measuring the distance between two points given two coordinates
transformation
a mapping, or movement, of all the points of a figure in a plane according to a common operation
rigid motion
a transformation of points in space
translation
a rigid motion that 'slides' each point of a figure the same distance and direction. Sliding a figure left of right is horizontal , and sliding it up or down is vertical.
pre-image
the original figure
image
the new figure created from translation
arc
part of a circle or a curve between two points
midpoint
a point that is exactly halfway between two given points
midpoint formula
the formula for finding the midpoint between to points given their coordinates
segment bisector
a line, line segement or ray that divides a line segment into two line segments of equal measure, or two congruent line segments
angle
formed by two rays or line segments that share a common endpoint.
angle bisector
a ray drawn through the vertex of an angle and divides the angle into angles of equal measure, or two congruent angles
point-slope form
equation for a line given the slope and a coordinate
perpendicular bisector
a line, line segment or ray that bisects a line segment and is also perpendicular to the line segment
concurrent
three of more lines, rays, or line segments that intersect at at certain point
point of concurrency
the point at which concurrent lines rays or segments intersect
circumcenter
the point of concurrency of the three perpendicular bisectors of a triangle
incenter
the point of concurrency of the three angle bisectors of a triangle
median
a line segment that connects a vertex to the midpoint of the opposite side in a triangle
centroid
the point of concurrency of the three medians of a triangle
altitude
a line segment that is perpendicular to a side of the triangle and has one endpoint at the opposite vertex
orthocenter
the point of concurrency of the three altitudes of a triangle