Download Isosceles Triangles

SWBAT apply & identify the equilateral and
isosceles triangle theorem (4.5)
Warm-Up: wks day 28 (#37-44)
*hw/hw log/regular wkb p. 107
Tab: Storybook “Congruent Triangles” in bucket A
Attach your rubric & put Tissue Box Project in
“Your Block Box”
Homework (day 28):
Honors: p. 253 (2, 5, 6-21, 23, 27, 30-32)/Quiz
(new constructions included)
Regular: wkb p. 107-108 (1-18 and 21-23)/Quiz
(new constructions included)
Pearsonsuccess.net due Friday!
Second Nine Weeks Extra Credit
• Benchmark 2- pearsonsuccess.net
This will close on January 17, 2015.
After you take this, if you would like it to count,
please give me a piece of paper with your name
and block and tell me you want me to count it
and I will enter it into HAC
Properties of Isosceles Triangles
An isosceles triangle is a triangle with two congruent sides.
Therefore, how many congruent angles would there be?
Label the following:
Vertex angle, Base angle
Leg, Base
A
C
Day 28 Notes:
Isosceles Triangle Theorem- if two sides of a triangle
are congruent
opposite angles are congruent
(base angles)
If AB  AC , then B  C.
A
The converse is also true……
If B  C , then AB  AC.
B
C
DE  CD, BC  AC , mCDE  120
Find the value of x.
A
mBAC  ______
D
3x - 7
x+15
B
B
C
50 
50 
C
A
E
B
• Name Two Congruent Angles:
C
A
• Name Two Congruent Segments:
D
Properties of Equilateral Triangles
A triangle is equilateral if and only if it is equiangular.
C
A
Each angle of an equilateral triangle measures 60°.
C
60°
60°
A
60°
B
B
Let’s Practice
“Isosceles Triangle Worksheet”
………..or Stations
D
Given: AB  CB  BD
Prove:
CBD  CBA
C
B
A
Statement
1.
AB  CB  BD
2.
D  DCB
3.
4.
5.
A  ACB
ABC  DBC
CBD  CBA
Reason
Triangle EFG is equilateral, and
segment EH bisects angle E
Find the following:
m<FEH= _____
m<F= _____
m<GHE= _____
E
F
Classify Triangle FHE ______
Classify triangle GEF ______
H
G