Illustrator: how to get part of an image resized exactly with the rest proportionate?

[Soliloquy]

More than once, I've found myself wanting to resize an image in Illustrator so that some element of the image is a specific size, while the rest of the image grows or shrinks in proportion. So far the only method that somewhat works is to draw a rectangle of the needed size, and then resize the image until the element fills the rectangle, but often the rectangle disappears. Are there any other methods of doing this?

 

[DrRipley]

I'm not sure if I understood your question well enough, but from what I gather, I think what you are aiming to do might be best or easier achieved with Photoshop. Illustrator, in my opinion, is best used for creating vector objects and layouts as opposed to editing existing JPEGS in the form of photos. That being said, editing photos as you've described isn't entirely impossible with Illustrator, just more difficult, personally speaking. What I'd do in this situation is to just make two layers of the photo, eliminate the unwanted portions on top of the first by using clipping mask, and then resizing to the desired size. It also helps to press shift before clicking and dragging the sizing box to keep the proportion intact while resizing.