Hey people.
If the formula for a rotation of 90 degrees is R90deg (x,y) = (-y, x)
Then what would be the final product for a Rotation of 90 degrees for (-1, 3) ?
I know some people might say that the final answer should be (-3, -1)
But then shouldn't Y now be positive according to the formula? This is where my confusion lies.
Rotation Question (10th Grade Geometry!)?
2015-11-15 8:24 pm
回答 (2)
2015-11-15 8:39 pm
It's a 90° rotation counterclockwise. The original point is in the 2nd quadrant and it rotates to the 3rd quadrant.
The signs in front of x and y are relative. That means they either stay the same (in the case of x --> x) or change (in the case of y --> -y). And they are swapped.
So you have the correct transformation:
(-1, 3) is transformed to (-3, -1)
See the diagram below:
The signs in front of x and y are relative. That means they either stay the same (in the case of x --> x) or change (in the case of y --> -y). And they are swapped.
So you have the correct transformation:
(-1, 3) is transformed to (-3, -1)
See the diagram below:
2015-11-15 8:39 pm
Why would it be positive? I don't understand what you find confusing.
收錄日期: 2021-04-21 15:03:19
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