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congruent triangles (and polygons)

all pairs of corresponding parts are congruent

reflexive property

when the side or angle is congruent to itself

SSS

if there exists a correspondance between the vertices of two triangles such that 3 sides of one triangle are congruent to the corresponding sides of the other triangle, the two triangles are congruent

SAS

if there exists a correspondance between the vertices of two triangles such that 2 sides and the included angle of one triangle are congruent to the corresponding part of the other triangle, the two triangles are congruent./

ASA

if there exists a correspondance between the vertices of two triangles such that 2 angles and the included side are congruent to the corresponding parts to the other triangle, the two triangles are congruent.

CPCTC

corresponding parts of congruent triangles are congruent

rim

the outline of a circle

center

how the circle is named by

radii

all _________ of a circle are all congruent

median

a line segment dran from any vertex of the triangle to the midpoint of the opposite side.

altitude

a line segment drawn from any vertex of the triangle to the opposite side, extended if necessary, and perpendicular to that side.

auxiliary lines

connect two points already in the diagram (usually)

2 points

__________ determine a line, ray, or segment

centroid

the point where 3 medians of a triangle intersect

orthocenter

the point of concurrency for the altitudes of a triangle

circumcenter

the point of intersection for the perpendicular bisectors of a triangle

auxiliary line

a line that can be added to a figure to help solve a problem or a proof

incenter

the point of concurrency for the angle bisectors of a triangle

scalene

a triangle in which no two sides are congruent

isosceles

a triangle in which at least two sides are congruent

base angles

the two congruent angles by the base of an isosceles triangle

vertex angle

the angle of an isosceles triangle with the 2 included sides

equilateral

a triangle in which all sides are congruent

equiangular

a triangle in which all angles are congruent

acute

a triangle in which all angles are acute

right

a triangle in which one of the angles is a right angle

hypotenuse

the side opposite the right angle

legs

the sides that form the right angle;

the sides that form the vertex angle

the sides that form the vertex angle

obtuse

a triangle in which one of the angles is an obtuse angle