In Equatio Mathspace, it’s very easy to annotate on top of other images because mathspace provides a template with lots of flexibility.  Once ‘Shapes’ are inserted, or ‘Smart Shapes,’ like a Protractor, you can then use the tool to measure the angles.  Now that the angle measure has been calculated, a user simply can use a different input method to enter the degrees for example. Take the angle measure once inserted and then drag it on top of the geometric figure to identify the correct angle measure.  You may even use the freehand drawing tool and annotate right over the shape.