Question

What would the coordinates (2, -2) be after a 90 degree counterclockwise rotation?

Answer 1

about what do we rotate?...Let (2,-2)=A.If I assume we rotate about the origin, we know OA=2sqrt2 and the angle OA creates with the x axis is -45 deg. Since we're rotating 90 deg counterclockwise and the image,A', must lie on the same circle (with center O) as A by definition of a rotation, we are searching for 2sqrt2(cos 45,sin45)=2,2

Answer 2

That formula is invalid?

Answer 3

sorry the formular wud be (x,y)->(x,-y)