1. Warm-Up Exercises Lesson 4.3, For use with pages 234-239 ANSWER ∆MNO ∆PRQ 1. Write a congruence statement. M NO P R Q

2. Warm-Up Exercises Lesson 4.3, For use with pages 234-239 ANSWER Third s Thm. 2. How do you know that N R ? M NO P R Q

3. Warm-Up Exercises Lesson 4.3, For use with pages 234-239 ANSWER 30 3. Find x. (7x – 50)º (2x + 10)º (3x)º

4. Warm-Up Exercises EXAMPLE 1 Use the SSS Congruence Postulate

5. Warm-Up Exercises EXAMPLE 1 Use the SSS Congruence Postulate Write a proof. GIVEN KL NL, KM NM Proof It is given that KL NL and KM NM By the Reflexive Property, LM LN. So, by the SSS Congruence Postulate, KLM NLM PROVE KLM NLM

6. Warm-Up Exercises Three sides of one triangle are congruent to three sides of second triangle then the two triangle are congruent. GUIDED PRACTICE for Example 1 Decide whether the congruence statement is true. Explain your reasoning. SOLUTION Yes. The statement is true. 1. DFG HJK Side DG HK, Side DF JH,and Side FG JK. So by the SSS Congruence postulate, DFG HJK.

7. Warm-Up Exercises GUIDED PRACTICE for Example 1 Decide whether the congruence statement is true. Explain your reasoning. SOLUTION 2. ACB CAD BC AD GIVEN : PROVE : ACB CAD PROOF: It is given that BC AD By Reflexive property AC AC, But AB is not congruent CD.

8. Warm-Up Exercises GUIDED PRACTICE for Example 1 Therefore the given statement is false and ABC is not Congruent to CAD because corresponding sides are not congruent

9. Warm-Up Exercises GUIDED PRACTICE for Example 1 Decide whether the congruence statement is true. Explain your reasoning. SOLUTION QT TR, PQ SR, PT TS GIVEN : PROVE : QPT RST PROOF: It is given that QT TR, PQ SR, PT TS. So by SSS congruence postulate, QPT RST. Yes the statement is true. QPT RST 3.

10. Warm-Up Exercises EXAMPLE 2 Standardized Test Practice SOLUTION By counting, PQ = 4 and QR = 3. Use the Distance Formula to find PR. d= y 2 –y 1 ( ) 2 x 2 –x 1 ( ) 2 +

11. Warm-Up Exercises EXAMPLE 2 Standardized Test Practice = 25 5 = By the SSS Congruence Postulate, any triangle with side lengths 3, 4, and 5 will be congruent to PQR. = + 1–4 ( ) 2 – 1 (– 5 ( ) ) 2 – PR = 4 2 + (– 3 ) 2 = 4 2 + 2 5 = (–4) – (–1) ( ) 2 5 – 1) ( 2 + = 25 ) The correct answer is A.ANSWER The distance from (–1, 1) to (–1, 5) is 4. The distance from (–1, 5) to (–4, 5) is 3. The distance from (– 1, 1) to (–4, 5) is

12. Warm-Up Exercises GUIDED PRACTICE for Example 2 JKL has vertices J(–3, –2), K(0, –2), and L(–3, –8). RST has vertices R(10, 0), S(10, – 3), and T(4, 0). Graph the triangles in the same coordinate plane and show that they are congruent. 4. KJ = SR = 3.ANSWER JL = RT = 6. LK = TS = 3 5.

13. Warm-Up Exercises EXAMPLE 3 Solve a real-world problem Structural Support Explain why the bench with the diagonal support is stable, while the one without the support can collapse.

14. Warm-Up Exercises EXAMPLE 3 Solve a real-world problem The bench with a diagonal support forms triangles with fixed side lengths. By the SSS Congruence Postulate, these triangles cannot change shape, so the bench is stable. The bench without a diagonal support is not stable because there are many possible quadrilaterals with the given side lengths. SOLUTION

15. Warm-Up Exercises GUIDED PRACTICE for Example 3 Determine whether the figure is stable. Explain your reasoning. SOLUTION The figure is without a diagonal support is not stable Because there are many possible quadrilaterals with the given side lengths. 5.

16. Warm-Up Exercises GUIDED PRACTICE for Example 3 Determine whether the figure is stable. Explain your reasoning. SOLUTION The diagonal support forms triangle with fixed side length by SSS congruence postulate, these triangles can not change shape. The figure is stable. 6.

17. Warm-Up Exercises GUIDED PRACTICE for Example 3 Determine whether the figure is stable. Explain your reasoning. SOLUTION The diagonal support is not stable because the lower half of figure dies not have diagonal support. 7.

18. Warm-Up Exercises Homework: 236: 1-10, 13-20, 22-26, 28, 29