it does not do to dwell on dreams… and forget to live. -dumbledore 4.5: isosceles and equilateral...
TRANSCRIPT
It does not do to dwell on dreams… and forget to live.-Dumbledore
4.5: Isosceles and Equilateral Triangles
Isosceles Triangles
The congruent sides are the LEGS.
The third side is the BASE.
The two congruent sides form the VERTEX ANGLE.
The other two angles are the BASE ANGLES.
Theorems
Theorem 4.3: Isosceles Triangle Theorem – If two sides of a triangle are congruent, then the angles opposite those sides are congruent.
BA
Theorems
Theorem 4.4: CONVERSE of Isosceles Triangle Theorem – If two angles of a triangle are congruent, then the sides opposite the angles are congruent.
BCAC
Theorems
Theorem 4.5: The bisector of the vertex angle of an isosceles triangle is the perpendicular bisector of the base.
ABCDABCD bisects and
Proof of the Isosceles Triangle Theorem
ZY
YXZXBXZXY
:Prove
bisects , :Given
Statements Reasons
1.
2.
3.
4.
5.
1.
2.
3.
4.
5.
YXZXB
XZXY
bisects
,
XBXB XZBXYB
ZY
21
Applications
Explain why each statement is true.
a. SWVS
b. TSTR
Applications
Find the value of y.
Corollaries
corollary – a statement that follows immediately from a theorem
Corollary to Theorem 4.3: If a triangle is equilateral, then the triangle is equiangular.
ZYX
Corollary to Theorem 4.4: If a triangle is equiangular, then the triangle is equilateral.
ZXYZXY
4.5: Isosceles and Equilateral Triangles
I don't know half of you half as well as I should like, and I like less than half of you half as well as you deserve.
-Bilbo
Homework 4.5: #1-13, 15, 20, 22, 28, 30
I don't know half of you half as well as I should like, and I like less than half of you half as well as you deserve.