I have a diagonal line and I want it to be the radius of a circle. I can snap the centre of the circle to the first cusp node fine and extend it out from there, but for some reason it won't snap the path of the circle to the other cusp node. What am I doing wrong here and how can I circumvent it?
In Inkscape 1.0, you can use a path effect for it, no snapping required:
- draw the diameter instead of the radius, then
- Path > Path effects > + > Ellipse from points : dropdown 'force circle'.
- select the radius
- Path > Path effects > + > Show experimental > Circle (by center and radius)
In the Snapping Controls bar, make sure you select the following options.
- Enable Snapping
- Snap Nodes Paths and Handles
- Snap to Paths
- Snap other Points
- Snap rotation centres
With the Bézier Tool selected, When you approach the circle's path, it will snap to it displaying "Handle to Path".
Example (snapping options shown right)
If you need to do this in reverse, and already have a line, then you could use the Measure Path extension to measure it, then draw a circle from one of the end nodes, holding down Ctrl+Alt as you click and drag, then edit the Rx and Ry values in the Tool Controls Bar to match the line length.
Just in case the radius is already drawn but you must insert a circle like in your example try this:
Have all snaps to point and guides ON, but keep snap to grid and bounding box OFF.
Drag from the top a horizontal guide to the center of the wanted circle. It snaps.
Duplicate (=select, press Ctrl+D) the radius. Drag duplicate's (=green) rotation center to the center of the wanted circle. It snaps. Rotate the duplicate to horizontal. It snaps, too.
Draw a vertical line (blue) starting from the end oft the rotated duplicate
Draw a circle from the wanted center point (=hold Shift and Ctrl) until it snaps to the vertical line.