Geometry: Transformations

[rachelmaddie]

I need help understanding this concept.

 

[rachelmaddie]

Question #2
r(270°,0)(x,y) = (y, -x)

F’ = r(270, 0)(-3,2) = (2, -3)
G’ = r(270°, 0)(-3, -1) = (1, -3)
H’ = r(270°, 0)(-1, -1) = (1, -1)
I’ = r(270°, 0)(0, 1) = (1, 0)

Is this correct?

 

[pka]

Question #2
r(270°,0)(x,y) = (y, -x)
F’ = r(270, 0)(-3,2) = (2, -3) NO
G’ = r(270°, 0)(-3, -1) = (1, -3) NO
H’ = r(270°, 0)(-1, -1) = (1, -1) NO
I’ = r(270°, 0)(0, 1) = (1, 0) YES?

It is \(\displaystyle (x,y)\to(y,\Large\bf-x)\)
Why did you not use the \(\displaystyle \bf -x\) part ?

 

[rachelmaddie]

It is \(\displaystyle (x,y)\to(y,\Large\bf-x)\)
Why did you not use the \(\displaystyle \bf -x\) part ?

Okay, I did not realize your suppose to keep the original sign.
F’ = r(270, 0)(-3,2) = (2, -3)
G’ = r(270°, 0)(-3, -1) = (-1, -3)
H’ = r(270°, 0)(-1, -1) = (-1, -1)
I’ = r(270°, 0)(0, 1) = (1, 0)

 

[pka]

Okay, I did not realize your suppose to keep the original sign.
F’ = r(270, 0)(-3,2) = (2, -3)
G’ = r(270°, 0)(-3, -1) = (-1, -3)
H’ = r(270°, 0)(-1, -1) = (-1, -1)
I’ = r(270°, 0)(0, 1) = (1, 0)

You just do not understand the notation, do you?
The correct answers are \(\displaystyle F': (2,3),~G': (-1, 3),~H': (-1,1)\)
You study those and come back and explain each. You must do that to get anymore help.

 

[rachelmaddie]

You just do not understand the notation, do you?
The correct answers are \(\displaystyle F': (2,3),~G': (-1, 3),~H': (-1,1)\)
You study those and come back and explain each. You must do that to get anymore help.

You just do not understand the notation, do you?
The correct answers are \(\displaystyle F': (2,3),~G': (-1, 3),~H': (-1,1)\)
You study those and come back and explain each. You must do that to get anymore help.

Can you please show me?

 

[rachelmaddie]

Can you please show me?

My textbook does not explain this. I only have the rules.

 

[Dr.Peterson]

When they say here, r_(90°,0)(x,y) = (-y, x), what they are saying is that if you start with a point (x, y), then the point you get after the rotation is (-y, x), using those particular values.

For example, if you start with the point G(2, 3), then "x" is 2 and "y" is 3; so "-y" is -3 and "x" is 2, so the resulting point is (-3, 2), as they show. You are substituting the coordinates of your point in the formula you are given.

Possibly it would help us if we knew more of your background. Have you learned about function notation, which is essentially what this is? Have you used formulas in other contexts? Also, do you have a teacher, in addition to the book? I understand that it can be hard to follow written instructions because they don't know how much you understand; that's why teachers (and face to face tutors) are so valuable. You can ask them questions and show how you are thinking. Similarly, when you ask someone online, the more you show of your own thinking, the better we can help.

 

[rachelmaddie]

When they say here, r_(90°,0)(x,y) = (-y, x), what they are saying is that if you start with a point (x, y), then the point you get after the rotation is (-y, x), using those particular values.

For example, if you start with the point G(2, 3), then "x" is 2 and "y" is 3; so "-y" is -3 and "x" is 2, so the resulting point is (-3, 2), as they show. You are substituting the coordinates of your point in the formula you are given.

Possibly it would help us if we knew more of your background. Have you learned about function notation, which is essentially what this is? Have you used formulas in other contexts? Also, do you have a teacher, in addition to the book? I understand that it can be hard to follow written instructions because they don't know how much you understand; that's why teachers (and face to face tutors) are so valuable. You can ask them questions and show how you are thinking. Similarly, when you ask someone online, the more you show of your own thinking, the better we can help.

No, I am not familiar with function notation. This is all new to me. This is an online geometry course and I’ve asked the teacher for help but the only form of learning is in the textbook.