Why do pictures look wider when rotated?

Question: Why do pictures look wider when rotated!?

i used the rotation thing in windows picture viewerWww@QuestionHome@Com

Best Answer - Chosen by Asker:

the viewer probably re-proportions the image to fit in the given aspect ratio!.

400 x 600 -this could be your image size -400 wide

when you rotate it in that program the 600 becomes the wide!.

in my picture viewer though, it rotates the entire canvas borders and all!.Www@QuestionHome@Com

they dont look wider!. they are wider!.
if you rotate a sheet of paper does it look wider!?
why would a pic be different!.Www@QuestionHome@Com