Geometry Drill 10/8/12

1. Geometry Drill 10/8/12 • Aki, Bard, and Coretta live in Albany, Biloxi, and Chicago. No one lives in a city that begins with the same letter as her name. Aki writes letters to her friend in Chicago. Who lives in what city? #??

2. Objectives Identify, write, and analyze the truth value of conditional statements. Write the inverse, converse, and contrapositive of a conditional statement.

3. Vocabulary conditional statement hypothesis conclusion truth value negation converse inverse contrapostive logically equivalent statements

4. By phrasing a conjecture as an if-then statement, you can quickly identify its hypothesis and conclusion.

5. Vocabulary • Conditional statement • A statement written in the form IF___,THEN___. • If P, then Q. • P –> Q (NOTATION)

6. Vocabulary Conditional statements: • If P, then Q • P implies Q • Q, if P ALL MEAN SAME THING

7. Vocabulary • Hypothesis-statement following the word “if”. • Conclusion-statement following the word “then”.

8. FACT OR FICTION??? IF TWO ANGLES ARE SUPPLEMENTARY, THEN THEY ARE BOTH RIGHT ANGLES.

9. REVERSE THE HYPOTHESIS & CONCLUSION

10. FACT OR FICTION??? IF TWO ANGLES ARE RIGHT ANGLES, THEN THEY ARE SUPPLEMENTARY ANGLES.

11. VOCABULARY • CONVERSE- A conditional statement with the hypothesis and conclusion interchanged. • If Q, then P. Q –>P

12. FACT OR FICTION??? If x = 4, then x2 = 16

13. Is the converse true? If x2 = 16, then x = 4.

14. Write the converse. Is the converse true? 1. If two angles are vertical , then they are congruent. 2. If x > 0, then x2 > 0.

15. The negation of statement p is “not p,” written as ~p. The negation of a true statement is false, and the negation of a false statement is true.

19. Example 4: Biology Application Write the converse, inverse, and contrapositive of the conditional statement. Use the Science Fact to find the truth value of each. If an animal is an adult insect, then it has six legs.

20. Example 4: Biology Application If an animal is an adult insect, then it has six legs. Converse: If an animal has six legs, then it is an adult insect. No other animals have six legs so the converse is true. Inverse:If an animal is not an adult insect,then it does not have six legs. No other animals have six legs so the converse is true. Contrapositive:If an animal does not have six legs,thenit is not an adult insect. Adult insects must have six legs. So the contrapositive is true.

21. Check It Out! Example 4 Write the converse, inverse, and contrapostive of the conditional statement “If an animal is a cat, then it has four paws.” Find the truth value of each. If an animal is a cat, then it has four paws.

22. Check It Out! Example 4 If an animal is a cat, then it has four paws. Converse:If an animal has 4 paws,then it is a cat. There are other animals that have 4 paws that are not cats, so the converse is false. Inverse: If an animal is not a cat, thenit does not have 4 paws. There are animals that are not cats that have 4 paws, so the inverse is false. Contrapositive: If an animal does not have 4 paws, thenit is not a cat; True. Cats have 4 paws, so the contrapositive is true.

23. If-Then Transitive Property (postulate) • Given: If A, then B. If B, then C. • Conclusion: If A, then C. (logic chain)

24. If yellow is brown, then red is blue. • If black is white, then yellow is brown. • If red is blue, then green is orange.

25. If black is white, then yellow is brown. • If yellow is brown, then red is blue. • If red is blue, then green is orange.

26. Write as a conditional ALL MATH TEACHERS ARE MEN.

27. WRITE IN IF-THEN FORM. IF A PERSON IS A MATH TEACHER, THEN THEY ARE A MAN.

28. A VENN DIAGRAM is sometimes used in connection with conditionals

29. If p , then q. p q

30. Make a Venn diagram If Ed lives in Texas, then he lives south of Canada

31. Venn Diagram Texas South of Canada If Ed lives in Texas, then he lives south of Canada. Texas

32. Counterexample South of Canada If Ed lives south of Canada, then he lives in Texas. Texas Ed lives in Maryland