21 terms

# H. Geometry Midterm: vocabulary

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points that lie on the same line
collinear
points that do not lie on the same line
noncollinear
a mathematical statement that can be proved
theorem
an unproved assumption
postulate
two collinear rays that have a common endpoint and extend in different directions
opposite rays
a pair of angles such that the rays forming the sides of one and the rays forming the sides of the other are opposite rays
vertical angles
a perpendicular segment from a vertex of a triangle to the opposite side
altitude
a line introduced into a diagram for the purpose of clarifying a proof
auxiliary line
a polygon in which each interior angle has a measure less than 180
convex polygon
lying in the same plane
coplanar
the length of the shortest path between two objects
distance
the first and fourth terms of a proportion
extremes
the point of intersection of a line and a plane
foot
the second and third terms of a proportion
means
the point of concurrency of the altitudes of a triangle
orthocenter
the point of concurrency of the perpendicular bisectors of the triangle's sides
circumcenter
the point of concurrency of the medians of a triangle
centroid
an equation stating that two or more ratios are equal
proportion
a quotient of two numbers
ratio
a polygon that is both equilateral and equiangular
regular polygon
two lines that are not coplanar
skew lines