Download Chapter 4 - Humble ISD

Hot Topics Chapter 4.1, 4.2, 4.3, and 4.8
Def. Of  's
Two Triangles are

if and only if all sides are

AND all <’s are

.
CPCTC-corresponding parts of congruent triangles are congruent. (Use only after
 's
are stated).
Classification of Triangles by Sides:
Equilateral triangles have 3 congruent sides
Isosceles triangles have at least two congruent sides
Scalene triangles have NO congruent sides.
Classification of Triangles by Angles:
An acute triangle has 3 acute angles.
An equiangular triangle is a special type of acute triangle. An equiangular triangle has 3  <’s.
A right triangle has exactly one right angle.
An obtuse triangle has exactly one obtuse angle.
Properties of
 's :
Reflexive – every triangle is  to itself
Symmetric If ABC  PQR, then PQR  ABC
Transitive If ABC  PQR and PQR  TUV, then
TRIANGLE SUM Theorem—The sum of the measures of the <’s of
If 2 <’s in one

to 2 <’s in 2nd
The acute <’s of right
 3rd pair of <’s
ABC 
TUV.
= 180

are complementary.
The measure of an exterior < of a
Measure of an exterior < of a
= sum of the two remote interior <’s.
is greater than either remote interior <.
ISOSCELES TRIANGLE THEOREM--If 2 sides of a triangle are  , then the <’s opposite those
sides are  .
CONVERSE OF ISOSCELES TRIANGLE THEOREM—If 2 <’s of a triangle are  , then the
sides opposite those <’s are  .
Every equiangular triangle is also equilateral.
Every equilateral triangle is also equiangular.