Is the first option in the arc meant for smaller arcs?
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When using the option/alt key to change the modes with the arc tool, line → half arc → arc → direction flip → repeat. the first one option does not seem to make sense to me because I always end up creating a large shape - unless its intention is not to do so but instead create a small arc?
Like this?

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@Boldline The line is used to add line segments to this shape. If you want to close a line with a full circle this will create a very large circle as the curvature here is zero (resulting in infinite radius). So this will be a use case which should not be used.