1. Mr. Saucedo
Geometry
Milby High School

2. OBJECTIVE:
To find the measures of the parts of isosceles and
equilateral triangles.

3. REVIEW

4. BASE ANGLES THEOREM
DEFINITION
If two sides of a triangle are congruent, then the angles
opposite to them are congruent.
VISUAL
LABEL:
If AB = AC, then m<B = m<C.

5. DEFINITION:
If two angles of a triangle are congruent, then the sides
opposite to them are congruent.
VISUAL
LABEL
If m<B = m<C, then AB = AC.

6. EQUILATERAL TRIANGLE
COROLLARY
DEFINITION
If a triangle is equilateral, then it is equiangular.
If a triangle is equiangular, then it’s equilateral.
VISUAL

7. GUIDED EXAMPLE 1
Triangle ABC is isosceles, where
AB = BC. Answer the following:
1. If the m<A = 75, then m<C = _____
2. If the m< B = 80, them m<A = ____
3. If c = 3, then a = ______
4. If a = 5, then c = ________

8. GUIDED EXAMPLE 2
Name the correct sides to make the statements true.
1. If m<D = m<E, then ______ = _______.
2. If m<2 = m<3, then _______ = _______.
3. If m<D=40, and m< E =40, then _______ = _______.

9. CHECKPOINT

10. CHECKPOINT:
Find the missing part.

11. GUIDED PROBLEM 3

12. GUIDED PROBLEM 4
Find the value of x.

13. GUIDED PROBLEM 5
Find the perimeter of the triangle.

14. CHECKPOINT
Find the perimeter of the triangle.

15. Name __________________________________
Date ___________________
LESSON 4.7
INDEPENDENT
PRACTICE
Independent Practice
For use with pages 264-270
Find the values of x and y.
1.
Find the perimeter of the triangle.
2.
3.
4.
Find the values of x, y, and z.
5.
7.
6.

16. HOMEWORK
SECTION 4.7, PAGES 79-81
PROBLEMS: 1, 4, 7, 8,
PRE-AP: ADD 17-19 (on separate sheet of paper)