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Crop Images with Clipping Mask to fit circles, squares or stroke outlines of other vector images.
Right Click the Rectangle Tool
Change it to the Circle Tool
Draw a Circle
Turn OFF the Stroke and Fill
Click and Drag to Select the Image and the Circle (If you’ve done this correctly, there will be a blue line around both objects)
Look at the menu bar below, click Object, then Clipping Mask then Make:
Now, your photo should be shaped to fit the mask you created.
Remember: a clipping mask must sit on top of the Image (ie. clipping mask be above the image in the layers hierarchy) in order to work properly.