how to draw a semi circle

As a beginner I am trying to draw a semi circular arch over two parallel lines. I have managed to create a circle in the correct place and size using the 2 point circle tool, but cannot find a way to delete the unwanted half of the circle. Am I going about this the wrong way ?.

The easiest is to use Modify - Divide and cut up the circle at the intersection points and then delete the unwanted part.
Or directly draw a half circle with Curve - Center,Point,Angles. It's an arc then.

Thanks for the advice but I am no further forward. I am using windows 10 and have downloaded librecad 2.2.0. I seem to have only circle options on the toolbar and there is no curve tool option available. Have tried your other suggestion modify-divide but this does not work properly either. My, lines start on 0,0 and are 100mm apart and 200mm long and i have created a circle 100mm dia with its centre on the end of the lines, below is what happens !
modify-divide "specify entity to cut (ci- enter). "specify center" (50,200-enter). "specify point on circle"
(0,200-enter). At this point I was expecting to see something like "specify second point on circle" but what happens is it creates a second circle of the same size on top of the original and the command line reverts to "specify entity to cut". It is probably me but could there be problems with the windows 10 version of librecad especially as I am missing the curve toolbar.
 

In the left toolbar the curve tools group is named 'Freehand', in the top toolbars Tools - 'Curve'.

Divide tool: After it asks for the entity to cut click onto the existing circle. Then it asks for the cutting point. Click on the desired point with the appropriate snap icon activated. Now the circle is cut open at one point, it still looks like a circle. In the same way do a second cut on the circle somewhere else. Now the former circle consists of two arcs. Select one of it by mouseclick , the delete it with the delete key on the keyboard. Gone!
What you are doing is switching from uncompleted divide command to circle command, thus creating a new circle.

OK got it, done and thanks. Is there a beginners tutorial somewhere where I can get familiar with using the tools, and perhaps answer a lot of the "how to" questions.

Hi,

Please have a look at

https://forum.librecad.org/Tips-n-Tricks-f5531031.html
https://wiki.librecad.org/index.php?title=Main_Page

kosisme wrote

OK got it, done and thanks. Is there a beginners tutorial somewhere where I can get familiar with using the tools, and perhaps answer a lot of the "how to" questions.

Thanks, but was hoping there would be some kind of beginners video which I could follow.