1. Do Now: ≅ 𝐽𝐾
65°
115°
115°

2. Lesson 4-1: Congruent Figures
Goal: Identify congruent figures and their corresponding parts.

3. Key Words:
Corresponding parts (of congruent figures): The corresponding sides and angles in congruent figures. Congruent (figures): Two geometric figures that have exactly the same size and shape. When two figures are congruent, all pairs of corresponding angles and corresponding sides are congruent.

4. Example 1: List Corresponding Parts
Given that ∆𝑷𝑴𝑵≅∆𝑬𝑫𝑪 , list all corresponding congruent parts.
Corresponding Angles
∠𝑃≅∠𝐸
∠𝑀≅∠𝐷
∠𝑁≅∠𝐶
Corresponding Sides
∠𝑃𝑀≅∠𝐸𝐷
∠𝑀𝑁≅∠𝐷𝐶
∠𝑁𝑃≅∠𝐶𝐸

5. Example 2: Write a Congruence Statement
The two triangles below are congruent.
Identify all corresponding parts.
∠𝑲≅∠𝑸, ∠𝑯≅∠𝑷, ∠𝑱≅𝑹, 𝑲𝑱 ≅ 𝑸𝑹 , 𝑯𝑲 ≅ 𝑷𝑸 , 𝑯𝑱 ≅ 𝑷𝑹
Write a congruence statement.
∆𝑲𝑯𝑱≅∆𝑸𝑷𝑹

6. Example 3: Use properties of Congruent Triangles
In this figure, ∆𝑺𝑻𝑼≅∆𝑾𝑿𝒀.
Find the length of 𝑾𝑿 .
Find 𝒎∠𝑺.
110° 8

7. Name corresponding Parts and congruent triangles
∠𝑆≅∠𝑌, ∠𝑈≅∠𝑍, ∠𝑇≅∠𝑋
28°
𝑆𝑇 ≅ 𝑌𝑋 ,
𝑈𝑆 ≅ 𝑍𝑌 ,
𝑇𝑈 ≅ 𝑋𝑍 3

8. Example 4: Determine whether triangles are congruent
∆𝐷𝐸𝐹≅∆𝐺𝐸𝐹

9. Example 5: Determine whether Triangles are congruent

10. Checkpoint:
yes no
yes no ∠𝐹 ∠𝑍 𝐸𝐷 𝑌𝑍

11. Checkpoint:
105°
45°
11.6
8.5
∆𝐸𝐹𝐺≅∆𝐾𝐿𝐽

12. Assignment:
P 222 – 223 #’s 8 – 44 even.