# help with circle and radius

6 messages
Open this post in threaded view
|

## help with circle and radius

 Hi, How can I draw a circle with radius lines every 2,5 cm on circumference??? thanks in advance! Marco
Open this post in threaded view
|

## Re: help with circle and radius

 Administrator There are many ways. Why 2.5 cm? Usually, for drawing circle sections, an angle is given. With the angle you can use Line-Angle or Line-Relative Angle or draw a horizontal/vertical line and use Modify-Rotate to create the others. When the angle is 15° or a multiple of it, use Line-2 Points, snap on the circle center first and then hold SHIFT for the second point, this snaps to 15° angles. When the sections are symmetric in quarters, you can use Snap on Middlepoints and adjust the number of middle points in tool options bar to sections - 1, this snaps on the endpoints on the circumference then. When only the section length is given, do some simple math to calculate the angle and use above methods. C = 2 * r * PI Then the section angle is = 360° / C * 2.5 investing less than half an hour into Search function can save hours or days of waiting for a solution
Open this post in threaded view
|

## Re: help with circle and radius

 Oh wow, thank you very much! With Carnot's theorem I have now the angle, that is 3,1° Can I use decimals or I must input entire angle values?? I'll use Line-Angle but how can I set the origin of all my lines? (for ex. 100; 40) (that is the centre of a circle) thank you!!! Marco
Open this post in threaded view
|

## Re: help with circle and radius

 Administrator With 3,1° you need to draw 116 lines. Honestly? In this case draw only one line and use Modify-Rotate. See https://librecad.readthedocs.io/en/latest/ref/tools.html?highlight=rotate#modifySelect the line and then the tool Modify-Rotate. Watch the comments on the command line to see what is expected. Use Snap to Center to find exactly the center of the circle (or enter 100,40 in command line). Reference and target point are not that important, because you can change the angle in the options window popping up. There select Multiple Copies, set number to 115 and the Angle to 360/116. Right, you can add math terms in most input fields, what leads to more accuracy. I'm not sure if localization is working for numerical inputs. When 3,1 does not work, try English notation 3.1. With 3,1 the last sector may not match the others, because of accuracy of the angle, which may be 3,103448... If this is intended, using 3,1 is OK. But for 116 identical sectors use 360/116 and the last sector will be the same as all the others. investing less than half an hour into Search function can save hours or days of waiting for a solution