Download 4-6 Isosceles and Equilateral Triangles.notebook

4­6 Isosceles and Equilateral Triangles.notebook
February 23, 2016
In an Iscosceles Triangle we know there are two congruent sides. If I were to tell you that there are also two congruent angles, where would you expect them to be?
X
W
Y
4­6 Isosceles and Equilateral Triangles
Anytime you have congruent sides in a triangle, the angles across from those sides are also congruent.
Anytime you have congruent angles in a triangle, the sides across from them are also congruent.
4­6 Isosceles and Equilateral Triangles.notebook
February 23, 2016
We know isosceles triangles have two congruent sides. That
C
means the angles across from those sides are
congruent.
So, if AC = BC, what two angles are congruent?
A
B
Parts of an Isosceles Triangle:
1) The congruent sides are known as legs.
2) The congruent angles are known as base angles.
3) The non congruent angle is the Vertex.
4) The non congruent side is the base.
4­6 Isosceles and Equilateral Triangles.notebook
February 23, 2016
ex) Identify the congruent sides based on the congruent angles.
B
H
E
F
A
C
D
I
G
ex) Identify the congruent angles based on the congruent sides.
K
N
9in
M
Q
9in
P
L
J
R
O
ex) If <SQR = <QSR, what sides are congruent?
Q
4x ­ 2
R
S
Solve for X.
2x + 2
4­6 Isosceles and Equilateral Triangles.notebook
February 23, 2016
ex) Find the value of x in the triangle.
80O
2x
What if all three sides or all three angles are congruent?
This shows us that a triangle that is equilateral is always equiangular and vise versa.
4­6 Isosceles and Equilateral Triangles.notebook
February 23, 2016
If a segment bisects the Vertex, then is also bisects the base.
*Also
2x ­ 3
3x ­ 9
Classwork:
pg 289 2 ­ 6
to base
4­6 Isosceles and Equilateral Triangles.notebook
Homework:
pg. 290
15 ­ 22
February 23, 2016