# Geometry Definitions, Postulates, Theorems

Electronics - Devices

Oct 10, 2013 (4 years and 7 months ago)

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Geometry Definitions, Postulates, Theorems

4
-
2 Isosceles Triangles

Legs

the congruent sides of an isosceles triangle

Base

the third side

Base angles

the other two angles

Vertex angle

formed by the two congruent sides

Theorem 4
-
1

Isosceles Triangle Theorem

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

Theorem 4
-
2

The bisector
of the vertex angle of an isosceles triangle is the perpendicular
bisector of the base.

Theorem 4
-
3

Inverse of Isosceles Triangle Theorem

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

Corollary

to Isosceles Triangle Theorem

If a triangle is equilateral, then it is equiangular.

Corollary

to Converse of Isosceles Triangle Theorem

If a triangle is equiangular, then it is equilate
ral.

An
equilateral triangle

has three congruent sides. An
equiangular triangle

has
three congruent angles.