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congruent polygon

two figures that have the same size and shape such that their vertices can be matched up so corresponding parts ( angles and sides) of the figure are congruent

median

a segment that connects the vertex to the midpoint of the opposite side

altitude

perpendicular segment vertex to the lines that contains the opposite side

perpendicular bisector

a line, ray, or segment that is perpendicular to a side of the triangle at its midpoint

distance from a point to a line

the length of the perpendicular segment from the point to the line or plane

sss

If three sides of one triangle are congruent to three sides of another triangle, then the triangles are congruent.

SAS

If two side and the included angle of one triangle are congruent to two sides and the included angle of another triangle, then the triangles are congruent.

ASA

If two angles and the included side of one triangle are congruent to two angles and the include side of another triangle, then the triangles are congruent.

Isosceles triangle theorem

If two sides of a triangle are congruent, then the angles opposite those sides are congruent.

Corollary 1: An equilateral triangle is also equiangular

Corollary 2: An equilateral triangle has three 60 degree angles

Corollary 3: The bisector of the vertex angle of an isosceles triangle is perpendicular to the base ate its midpoint

Corollary 1: An equilateral triangle is also equiangular

Corollary 2: An equilateral triangle has three 60 degree angles

Corollary 3: The bisector of the vertex angle of an isosceles triangle is perpendicular to the base ate its midpoint

4-2

If two angles of a triangle are congruent, then the sides opposite those angles are congruent

AAS

If two angles and a non-inclulded side of one triangle are congruent to the corresponding parts of another triangle, then the triangles are congruent

HL Thereom

If the hypotenuse and a leg of one right triangle are congruent to the corresponding parts of another right triangle, then triangles are congruent

4-5

If a point lies on the perpendicular bisector of a segment, then the point is equidistant from the endpoints of the segment

4-6

If a point is equidistant from endpoints of a segment, then the point lies on the perpendicular bisector of the segment

4-7

If a point lies on the bisector of an angle, then the point is equidistant from the sides of the angle

4-8

If a point is equidistant form the sides of an angle, then the points lies on the bisector of the angle