Download Notes _____________________. Isosceles Triangles

Geometry
Notes - Section 4.5 Isosceles and Equilateral Triangles
Spring 2009
Isosceles Triangles
Theorem 4-3: Isosceles Triangle Theorem.
If 2 sides of a triangle are congruent, then the ______________ opposite the sides are
_____________________.
Theorem 4-4: Converse of the Isosceles Triangle Theorem
If 2 angles of a triangle are congruent, then the ___________ opposite the angles are
_______________.
Theorem 4-5:
The bisector of the vertex angle of an isosceles triangle is the ______________________
__________________ of the base segment.
Example 1: Complete each statement, why is it true?
1. VT  ______________
2. UT  ___________  YX
3. VU  __________
4. VYU  __________
Example 2: Find the values of missing variables
a.
b.
c.
d.
Geometry
Notes - Section 4.5 Isosceles and Equilateral Triangles
Spring 2009
Example 3:
Prove ADB  CBD
Example 4:
Solve for x and y.
Example 5:
Find the value of x
Equilateral Triangles
Corollary to Theorem 4-3: If a triangle is equilateral, then the triangle is also
______________________
Corollary to Theorem 4-4: If a triangle is equiangular, then the triangle is also
___________________.
What is the angle measure of each angle in an equilateral triangle? _______________
Example 6: Determine the measure of angles 1 and 2