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simplest representation in geometry
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## terms list

point
simplest representation in geometry
line
made up of a series of points; always straight
ray
has 1 endpoint which must be named first
segment
has 2 endpoints
collinear
3 or more points on the same line
noncollinear
3 or more points not on the same line
plane
a flat surface that contains non collinear points; has no end
parallel lines
lines or planes that do not intersect and are always equidistance apart
midpoint
divides a segment into 2 equal parts or segments
congruent
having the same measure; not official until measured
angle
a figure formed by 2 rays with the same endpoint
vertex
the common endpoint of an angle
sides of the angle
2 rays
protractor
the device used to measure angles
perpendicular lines
2 lines that intersect so that the angles are all congruent right angles
complementary angle
angles add up to 90 degrees
supplementary angle
sum of the angles is 180 degrees
straight angle
180 degree angle
angles that share a common vertex and common side but no interior points
right triangle
a triangle with one angle measuring 90 degrees
obtuse triangle
a triangle with 1 angle greater than 90 degrees
true for triangles
true or false: the sum of the length of 2 sides of a triangle is greater than the third side
180 degrees for triangle
the sum of all the measures of the angles inside a triangle
scalene triangle
a triangle with no congruent sides
isoceles triangle
a triangle with at least 2 congruent sides
equilateral triangle
a triangle with 3 congruent sides
polygon
a closed figure formed by joining straight segments
triangle
3 sided polygon
4 sided polygon
pentagon
5 sided polygon
hexagon
6 sided polygon
heptagon
7 sided polygon
octagon
8 sided polygon
nonagon
9 sided polygon
decagon
10 sided polygon
regular polygon
a polygon with all sides and angles congruent is considered...
diagonal
a segment that connects nonconsecutive vertices - formula n(n-3) / 2
parallelogram
a quadrilateral with 2 sets of parallel sides
rectangle
a quadrilateral with 2 sets of parallel sides and 4 right angles
rhombus
a quadrilateral with 2 sets of parallel sides and 4 congruent sides
square
a quadrilateral with 2 sets of parallel sides and 4 congruent sides and angles
trapezoid
a quadrilateral with 1 sets of parallel sides
circle
a set of points equidistance from the center
segment going from the center to any point of the circle
chord
segment containing 2 points on the circle
diameter
a chord passing through the center of the circle
circumference
distance around the circle
similar
geometric figures have the same shape, but not necessarily the same size
symmetry
describes the shape of a figure or object
reflective symmetry
a figure has this if it can be divided into two halves that are mirror images of each other
line of symmetry
a line that divides a figure into 2 halves that match exactly when the figure is folded on that line
rotational symmetry
the ability to rotate the figure around some point so that it concides with itself
center of symmetry
the point in the center of a figure that has rotation symmetry
measure
the number of degrees in an angle
acute angle
an angle less than 90 degrees but more than 0 degrees
bisector of an angle
the ray that divides the angle into two congruent adjacent angles
intersecting lines
Lines that cross at exactly one point
vertical angles
Two nonadjacent angles formed by two intersecting lines
transversal
A line that intersects two or more lines.
interior angles
angles on the inside of parallel lines cut by a transversal
exterior angles
angles on the outside of parallel lines cut by a transversal
corresponding angles
angles in the same place on different lines
alternate exterior angles
Angles that lie outside a pair of lines and on opposite sides of a transversal.
alternate interior angles
angles between 2 lines and on opposite sides of a transversal
perpendicular bisector
A line that is perpendicular to a segment at its midpoint.
convex of polygon
diagonals of polygon lie within the interior of the polygon, outward
concave of polygon
A polygon in which at least one vertex appear to be pushed inward.
base angles of triangle
other angles (isosceles triangle), The angles opposite the two equal sides in an isosceles triangles. A pair of angles that share a base as a common side in a trapezoid
acute triangle
a triangle with 3 acute angles (less than 90 degrees)
altitude of a triangle
of a triangle is a line segment drawn from a vertix of the triangle perpendicular to the side, every triangle has 3 altitude
altitude height of a triangle
of triangle is the length of the altitude
concurrent lines of a triangle
lines that intersect in a point within a triangle
orthocenter of a triangle
where the lines meet - concurrecy of the altitudes of a triangle
median of a triangle
is a line segment connecting a vertex of the traingle to the midpoint of the side oposite that vertex
centroid of a triangle
point of concurrency with with median lines
circumcenter of a triangle
point of concurrency with perpendicular bisector
congruent triangles
triangles for which corresponding sides are corresponding angles are congruent
angle bisector of a triangle
interior angles of a triangle
incenter of a triangle
point of concurrecy of angle bisector, center of circle drawn inside triangle
arc of a circle
is the set of points between and including two point on the circle
semicircle
Half of a circle, degree of measure of a emicircle is 180 degress
central angle of a circle
is an angle that has its vertix at the center of the circle, determines two arcs on a circle
minor arc of a circle
smaller of two arcs - measured in degrees
major arc of a circle
larger of two arcs - measured in degrees
inscribed angle of a circle
vertix is on a cirlec and whose sides are chords of the circle
intercepted are of a circle
interior arc of an inscribed angle and whose endpoints are on the sides of the angle
secant to a circle
line going through a circle, is a line that contains a chord
tangent to a circle
line touching outside of circle, is a line in the plane of the circle that intersects the circle in only one point.
concentric circles
are circles that have the ame center
sector of circle
is region bounded by two radii and an arc of the circle
polygon inscribed in a circle
if each of its vertices lies on the circle, polygon inside circle
polygon is circumscribed about a circle
if each of its sides is tangent to the circle, circle inside polgyon 13 items en gd

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