Mr. SaucedoGeometry

Milby High School

OBJECTIVE:To find the measures of the parts of isosceles

and equilateral triangles.

REVIEW

BASE ANGLES THEOREMDEFINITION

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.

DEFINITION:If two angles of a triangle are congruent, then

the sides opposite to them are congruent.

VISUAL

LABELIf m<B = m<C, then AB = AC.

EQUILATERAL TRIANGLECOROLLARYDEFINITION

If a triangle is equilateral, then it is equiangular.

If a triangle is equiangular, then it’s equilateral.

VISUAL

GUIDED EXAMPLE 1Triangle 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 = ________

GUIDED EXAMPLE 2Name 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 _______ =

_______.

CHECKPOINT

CHECKPOINT:Find the missing part.

GUIDED PROBLEM 3

GUIDED PROBLEM 4Find the value of x.

GUIDED PROBLEM 5Find the perimeter of the triangle.

CHECKPOINTFind the perimeter of the triangle.

INDEPENDENT PRACTICE

Name __________________________________ Date ___________________ LESSON 4.7 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. 6.

7.

HOMEWORKSECTION 4.7, PAGES 79-81

PROBLEMS: 1, 4, 7, 8,

PRE-AP: ADD 17-19 (on separate sheet of paper)