Bisect a Circle

How do I bisect a circle with a line so that the top and bottom sections of the circle are the same size?

Draw a circle. Draw a straight line with the Shape editor tool (hold CTRL key to keep it straight). Select circle and line and hit CTRL+Shift+L (or go to Arrange > Alignment). Select align centrally from either the top or bottom menus (depends whether your line was vertical or horizontal) and click Apply. Now go to Arrange > combine shapes > Slice.
Use the shape editor to edit the nodes or "break open" the resulting shapes so you actually get the arcs without the straight line in between them.

BTW, your line should be on top of the circle for this to work, not under it ;)

Here is a short video tutorial. :)

Here's another short video tutorial that illustrates how to get an arc of some precise central angle (not just a semicircle)

Thanks, cursor! Even though I didn't ask the question, your answers were simple and to the point...I believe even I could do that now.

Thanks again,
Bob

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Originally Posted by cursor

Here is a short video tutorial. :)

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Good clear voice their Curtis, unlike my mumbling :o

Couple things to speed up the task. You do not need to draw a line 'outside' of the circle to slice it into two halves.

Attachment 63591

Also, as mentioned by The Alien, the quicker way to split the ellipse into two unjoined arcs is to 'break' at the points.


Attachment 63593

Thanks.
I learn new stuff every day, Steve.
Problem is ... I sometimes forget it the day after! :eek:

I'll redo those two video tutorials (at some point), incorporating the more efficient techniques. :)

Thanks to all on showing these techniques in XARA and lending your experience. This is applicable in ALL versions right?

chuck

Yes (as far as I am aware). The techniques also work for Web Designer.

Actually Web Designer does not have the option to 'convert to editable shape' from an ellipse etc. Neither can it 'convert a line to a shape.'

See ... that's a fine example of the kind of thing that escapes one ... at my age. :eek:

Thanks for the clarification, Steve. :)

Another way, eliminating the slicing line, is to draw the circle, rotate 45 degrees if required (dependent on how the circle was created), convert to editable shapes, marquee select the east/west nodes, break at points.

You mean similar to image 2 in post#6 Egg? ;)

Yes, I just saw that !!! I got confused by the line in the upper screengrab. :o

At least we can all agree on that particular method. :)

A candidate for the RAQ's perhaps ;)?

Bob:

There are other ways to make a straight line segment have a specific angle without having to use snap to gride, rules, or interative rotating; provided the node is a cusp of line segment.


With Shape editor, select the node and in the infobar Line Angle box (denote by an A) and type in an angle (as an obsolute value). If a line "shrinks" or "grows" due to the new angle then, while the node is still selected, type in a length in the Line Legth box (denoted by an L)

The method is really convenient to quickly "squaring corners" of a complex line (input 90, 180, 270, or 0) or to restore a line to as specific angle when it has been distorted by non-uniform scaling.

I'm always pulling my hair out with this, as the circle nodes never align, are not on a 45 degree rotation, after slicing - additional nodes get caught up in the selection process (because they're the original nodes) which leaves me with less than a semi-circle - to name a few reasons lol.

Thanks, this way seems to be the easiest for me in trying all these ways:

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convert to editable shapes, marquee select the east/west nodes, break at points.

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Found out how to get the 45 degrees, create the circle by ctrl and drag out from a center point (eg via guides)

1 - Select circle
2 - Go to the middle of your screen, press ctrl and then left mouse & drag out to size
3 - Hit the pointer/selection tool and with mouse select circle
4 - (original 4 nodes should be at 45 degree 'X' points) Put 45 in the rotate box (top menu to the left of flip icons) and enter. They should now be at 90 degree '+' points
5 - Go to menu bar, Arrange, select Convert to editable shapes
6 - Select the shape tool (F4) and then just drag a 'selection' box as stated in the previous post above "West & East (marquee around the 2 nodes sitting at 9 and 3 on a clock). They should then appear red.
7 - Select 'break at points' icon (in the menu bar)
8 - (important) Select the pointer/selection tool, select anywhere outside the circle.
9 - Test it worked by selecting the top half of the circle with left mouse click. You should only see the 8 handles (selection bounds handles) for the top half semi-circle.

I've made a 1 minute video that shows each step. Sorry, about the size being too big to show on here. There's no viruses etc. http://www58.zippyshare.com/v/93439655/file.html

Hope this all helps someone like me. I can now do this very easily thanks to Egg :)

Hi puw, here's a video of a slight eccentricity in Xar's elipse creation that you may be unaware of. It can eliminate step 4.

By the way, I didn't watch your zippyshare video, I'm always dubious of downloading from sites I'm not familular with, too much malware about. Hope you don't mind.

Watch in HD

That's really helpful as I never noticed the three variant choices before (or if I did I didn't understand what they were or the differences between them, so left them in default 'radius').

For some reason, in creating an ellipse, I always held down the shift key. Now here's another oddity, depending on which of the three you choose from and then whether you choose shift or ctrl, the node positions vary. See screenshot:

Attachment 105213

About my vid egg, no problem & understand (that's why I mentioned no viruses etc). Zippyshare is a free file sharing service that works the best for me in my location. And yes, you have eliminated No. 4 :)

Now I know why I was getting such weird node angles and messing around with rotation values of 0.0025 lol.

Thanks again.

Your better off using Ctrl, as this restricts the shape to the same size in both directions, for example selecting a Rectangle or Ellipse constrains the shape to a Square or Circle.

The Shift option merely increase/decrease the dimensions of an already created shape in equal directions. For example try creating a circle using the shift key, it doesn't work (unless it's another restriction on Xara variant software)