Question

Which ordered pair gives the coordinates of the image of R(-a, b) if R is rotated clockwise 180°?

I tried every answer and it is still wrong.

(b, -a)
(a, -b)
(-b, -a)
(a, b)

Answer 1

If (x,y) is rotated 90 degrees anti-clockwise, then the new coordinates will be (-y, x). The x,y switch places and then you change the sign of the first coordinate.

Here, rotating clockwise by 180 degrees will be same as rotating 180 degrees anti-clockwise because both will end up in the same place. So start with (-a, b). First rotate it by 90 degrees by switching x and y and changing the sign of the first coordinate. Then rotate it again by 90 degrees by switching x and y and changing the sign of the first coordinate. What you get will be the result of rotating it 180 degrees.

Answer 2

I thought so but the options are not there I tried all my first answer was (a,b)
options:
(b, -a) (a, -b) (-b, -a) (a, b)

Answer 3

Are the four answers listed in your question the various choices to pick from?

Answer 4

yes, and I tried every one...:-(

Answer 5

(-a, b) after 90 degree rotation becomes (-b, -a). After another 90 degree rotation it becomes (a, -b).
So after 180 degree rotation R will be at (a, -b).

The online software could be wrong.

Answer 6

If there are only 4 choices and you tried them all and it says all of them are wrong then it must be some glitch in the software.

Answer 7

Another one of my question matching I got a partial credit,I checked everyone and I just cant get it.
1. (5, 2); 90° (-5, 2)
2. (5, 2); 180° (-5, -2)
3. (5, 2); 270° (-2, 5)
4. (-5, 2); 90° (-2, -5)
5. (-5, 2); 180° (2, -5)
6. (-5, 2); 270° (5, -2)
7. (-2, 5); 90° (5, 2)
8. (5, -2); 180° (2, 5)

Do you see where I went wrong?

Answer 8

Alpha Omega curriculum

Answer 9

Do the degrees represent anti-clockwise rotation or clockwise rotation?

Answer 10

Match the pre-image, and its clockwise rotation, with the coordinates of its image.

Answer 11

For all the 180 degree rotations, just change the signs of BOTH x and y.
270 degree rotation clockwise is same as 90 degree rotation anti-clockwise. Use the method I indicated in my very first reply.

Answer 12

Okay, thank you

Answer 13

I usually remember just one thing: For 90 degree rotation anticlockwise, switch x and y and change the sign of the first coordinate. All other rotations, 90, 180, 270, clockwise or anticlockwise can be arrived at just by remembering that one thing.

Answer 14

If I go 90 degrees CLOCKWISE, then I have to go 270 degrees ANTICLOCKWISE.
(x,y) after 90 degrees anticlockwise becomes (-y, x)
After 180 degrees anticlockwise becomes (-x, -y)
After 270 degrees anticlockwise becomes (y, -x)

Therefore, to go 90 degree CLOCKWISE, switch x and y and change the sign of the second coordinate.