Thread: Rectangle rotation

Heya all,

I've got a problem where I know the four corners of a rectangle that is rotated about its center by an unknown angle. I need to know the angle of rotation, and also the width and height of the rectangle if it was not rotated at all.

For the life of me, I can't see how I can determine that information with just the four corners of the rectangle. Any help would be greatly appreciated.

Originally Posted by Turtlebread

Heya all,

I've got a problem where I know the four corners of a rectangle that is rotated about its center by an unknown angle. I need to know the angle of rotation, and also the width and height of the rectangle if it was not rotated at all.

For the life of me, I can't see how I can determine that information with just the four corners of the rectangle. Any help would be greatly appreciated.

I did not see this before.

Post the coordinates of the four corners so that we can play on your question.

Rotating about the origin by angle counterclockwise is the same by multiplying by the matrix .

So if the centre of your rectangle is the origin, if one corner of the rectangle has co-ordinates , its co-ordinates after the rotation would be .