9/23/13 Warm Up

1.Q is between P and R. PQ = 2w – 3 and QR = 4 + w, and PR = 34. Find the value of w, PQ, AND QR.

2.Use the diagram to find the measures of angles 4 & 5.

68˚

GEOMTRY GAME PLANDate Monday, 9/23/13

Section / Topic 2.1 Conditional Statements

Lesson Goal Students will be able to recognize and analyze conditional statements.

Standard Geometry California Standard 4.0 Students prove basic theorems involving congruence.

Homework Per 4: Khan AcademyPer 6: Page 75: 9 – 21, 63 – 66

Announcement Late Start on Wednesday

Conditional Statement

A logical statement with 2 parts2 parts are called the hypothesis &

conclusionCan be written in “if-then” form; such as,

“If…, then…”Hypothesis is the part after the word “If”Conclusion is the part after the word

“then”

Ex: Underline the hypothesis & circle the conclusion.

If you are a brunette, then you have brown hair.

hypothesis conclusion

If two points lie on the same line, then they are collinear.

Rewrite the statement in “if-then” form

Ex 1: Vertical angles are congruent.If there are 2 vertical angles, then they are

congruent.If 2 angles are vertical, then they are congruent.

Ex 2: An object weighs one ton if it weighs 2000 lbs.If an object weighs 2000 lbs, then it weighs one

ton.

Ex 3: All monkeys have tails.If an animal is a monkey, then it has a tail

Counterexample

Used to show a conditional statement is false.

It must keep the hypothesis true, but the conclusion false!

Write a counterexample to prove the statement is false.

If x2 = 81, then x must equal 9.

Counterexample: x could be (-9) because (-9)2=81, but x≠9.

The hypothesis true, but the conclusion false!

Counterexample

Write a counterexample for the following statements:1) If a number is divisible by 2, then it is divisible by 4.

Counterexample: 10 is divisible by 2 but not 4.

2) If a bird is a swan, then it is white.

Counterexample: A swan can also be black.

Converse

Switch the hypothesis & conclusion parts of a conditional statement.

Ex: Write the converse of: “If you are a brunette, then you have

brown hair.” If you have brown hair, then you are a brunette.

Write the CONVERSE of the statement

1) If there is snow on the ground, then flowers are not in bloom.

Converse: If flowers are not in bloom, then there is snow on the ground.

2) If two segments are congruent, then they have the same measure.

Converse: If segments have the same measure, then they are congruent.

GEOMTRY GAME PLANDate Monday, 9/23/13

Section / Topic 2.1 Conditional Statements

Lesson Goal Students will be able to recognize and analyze conditional statements.

Standard Geometry California Standard 4.0 Students prove basic theorems involving congruence.

Homework Page 75: 9 – 21, 63 – 66

Announcement Late Start on Wednesday