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ANSWERS TO EVENS
2) FE||CD
4) FB||EC
6) AE||BC
8) None
10) AE||BD
12) FB||EC
14) None
16) AE||BD and AB||FC
18) x = 90, y = 130
20) PQ||RS
24) Given
Definition Angle Bisector
Substitution/Transitive
Alternate int. angles are cong., then lines are ||.
3-4 ANGLES OF TRIANGLES
TYPES OF TRIANGLES (BY SIDES)
Scalene
Isosceles
No congruent sides
Equilateral
2 congruent sides
3 congruent sides
TYPES OF TRIANGLES (BY ANGLES)
Acute
All acute angles
Right
1 right angle
Obtuse
1 obtuse angle
Equiangular
3 congruent angles
TERMS TO KNOW
Vertices (plural)
A
B
C
TRIANGLE ABC
B
Sides
AB
BC
AC
A
C
Angles: A, B, C
THEOREM
The sum of the measures of the angles of a
triangle is 180º
 All 3 angles must = 180 (Like Ang. Add. Post)

COROLLARY
(something that can be proven from a theorem)
If 2 angles of a triangle are cong. to 2 angles of
another triangle, then the 3rd angles are also
congruent.
C
Z
B
A Y
X
COROLLARY

Each angle of an equiangular triangle is 60º.
x  x  x  180


In a triangle, there can be at most 1 right or 1 obtuse
angle.
Acute angles of a right triangle are complementary.
EXTERIOR ANGLE THEOREM

The measure of an exterior angle of a triangle
equals the sum of the measures of the two remote
interior angles
100 Exterior Angle
80
70
30
Remote Interior Angles
TOO

Page 96 #9-11
Answers
9) 90°
10) 105°
11) 75°
Homework: Page 97 #1-20, 25
25: 5 steps, separate the triangles!
Flashcards: Both Theorems and any of the
triangles that you did not already know.