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Carlycan’tdomath03

Guest

I’m very confused plz help me (geometry)

1. If I have two points, A and B, name at least four geometric elements taught in Lesson 1 that I can create with only the two points. (For example, the name of a line through points X and Y would be written ln_XY.)

My answer: Line, line segment, ray, and point

2. If I have line DE and ray ED, can I prove I have a plane? Explain your answer.

My answer: No, you do not have a plane. I am assuming that they are on the same line, which goes against one of the “rules” to have a plane.

3. Write out the four logical forms of the statement: Cats make great pets.  (Label the four forms: statement, inverse, etc. and write them as If..then..)

My answer: If it’s a cat, then it’s a great pet.
                  If it’s a great pet, then it’s a cat.
                  If it’s not a cat, then it’s not a great pet.
                  If it’s not a great pet, then it’s not a cat.

4. Write a counterexample for the converse of "Cats make great pets."

My answer: A tiger is a cat, and it’s not a great pet.

5. Write out the four logical forms of the statement: Cars have four wheels. (Label the four forms: statement, inverse, etc. and write them as If..then..)

My answer: If it’s a car, it has four wheels.
                  If there are four wheels, then it’s a car.
                  If it’s not a car, then it doesn’t have four wheels.
                  If it doesn’t have four wheels, then it’s not a car.

6. Write a counterexample for the converse of "Cars have four wheels."

My answer: The aptera is a car, and it has three wheels.

These were the corrections my teacher gave me

#1 We are already given a point, so that is not a new element created. Please give each of these a name using the points A and B as shown in the example in the question.

#2 What is your reasoning for saying that these are on the same line?

#3, 5 Please label each of these: statement, converse, etc..

#4, 6 We want a counterexample of the converse.

I’m really confused and in need of some help, I have to get geometry done over the summer but this lesson has had me at a roadblock.
Any and all help would be very much appreciated,

Thx!

Jaspers

Member

Registered: 2019-05-24

Posts: 54

Re: I’m very confused plz help me (geometry)

Hello Carly.

4. Write a counterexample for the converse of "Cats make great pets."

My answer: A tiger is a cat, and it’s not a great pet.

This is not correct. The sentence can be rewritten “All cats are great pets”; the converse is then “All great pets are cats”. Now give an example of an animal that is a great pet but not a cat.

6. Write a counterexample for the converse of "Cars have four wheels."

My answer: The aptera is a car, and it has three wheels.

Again, not correct. The converse is “All things with four wheels are cars”. Give an example of something that has four wheels but is not a car.

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