Circle
The Circle tool lets you construct a circle in three different ways. You can define the center first and then a circumference point You can define a circumference point first and then the center or you can define the circle with two opposite circumference points.
You use the second Option Button to control this construction method. The third option button allows you to constrain the second point so that it’s perfectly horizontally aligned or vertically aligned with the first or so that it positioned along a vector you define using the Mark Button.
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