1. 4.7 Isosceles & Equilateral Triangles October 23, 2012
4.7 Isosceles and Equilateral Triangles vertex <
Legs: the 2 ≅ sides of an isosceles
Vertex Angle: the < formed by the legs
leg leg
Base: the 3rd side
Base Angles: the 2 <s adjacent to the base
< bas
se e <
ba
Base Angles Theorem: If 2 sides of a are ≅, base
then the < opposite them are ≅.
Converse of Base Angles: If 2 <s are ≅ ,
then the sides opposite them are ≅.
Oct 27­7:31 AM
HW pg. 267 #3­27 odd 1

2. 4.7 Isosceles & Equilateral Triangles October 23, 2012
Corollaries:
If a triangle is equilateral, then it is equiangular.
If a triangle is equiangular, then it is equilateral.
Find ST in the triangle at the right.
STU is equilateral, then its is equiangular.
Oct 27­3:53 PM
HW pg. 267 #3­27 odd 2

3. 4.7 Isosceles & Equilateral Triangles October 23, 2012
Oct 27­4:02 PM
HW pg. 267 #3­27 odd 3

4. 4.7 Isosceles & Equilateral Triangles October 23, 2012
Oct 27­4:03 PM
HW pg. 267 #3­27 odd 4

5. 4.7 Isosceles & Equilateral Triangles October 23, 2012
Find the values of x and y in the diagram.
y° = 120°
x° = 60°
Oct 27­4:05 PM
HW pg. 267 #3­27 odd 5

6. 4.7 Isosceles & Equilateral Triangles October 23, 2012
HW pg. 267 #3‐27 odd
Oct 27­4:11 PM
HW pg. 267 #3­27 odd 6