How to take a screenshot on Mac: How to print screen on a Mac
Now that you've captured the screen (or partial screen) that you want to print, you simply need to find the image (most of the techniques above will save it to the desktop, unless otherwise specified) and double-click to open it in Preview. Now hit Apple-P to print directly from Preview.
If you want to be more artful about the way you print the image - arranging it neatly within white space, including other images on the same printout and so on - you can drag the image on to Photoshop or open it in an Adobe InDesign document.
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