basty Posted January 26 Share Posted January 26 I would like to ask technical drawing method. How do you draw an arc with radius of 400 that passing through point A and tangent to red line? Thanks in advance Quote Link to comment Share on other sites More sharing options...
CyberAngel Posted January 26 Share Posted January 26 Here's a hint. If you offset the red line by 400, the center of your circle will be somewhere along that line. Quote Link to comment Share on other sites More sharing options...
basty Posted January 26 Author Share Posted January 26 (edited) I tried your instruction already. The result is, I can make a circle with radius of 400 and tangent to the red line and the offset one. Now how do I make it passing through point A? Edited January 26 by basty Quote Link to comment Share on other sites More sharing options...
CyberAngel Posted January 26 Share Posted January 26 Think about how to find that point on your offset line. You know it's 400 units away from Point A. Quote Link to comment Share on other sites More sharing options...
basty Posted January 26 Author Share Posted January 26 41 minutes ago, CyberAngel said: Think about how to find that point on your offset line. You know it's 400 units away from Point A. I tried your instruction but I can't do it to make it pass through point A. What should I do? Quote Link to comment Share on other sites More sharing options...
basty Posted January 26 Author Share Posted January 26 (edited) The problem is, if I make it tangent to the red line, it doesn't pass through point A. If I make it pass through point A, it doesn't tangent to the red line. I would like to ask also how do you locate the center point. Edited January 26 by basty Quote Link to comment Share on other sites More sharing options...
BIGAL Posted January 29 Share Posted January 29 You have to draw with construction lines and circles. Quote Link to comment Share on other sites More sharing options...
basty Posted January 31 Author Share Posted January 31 (edited) Thank you for the reply. I am sorry, I still don't understand. Can you show me the construction geometry with dimensions like mine? Thanks Edited January 31 by basty Quote Link to comment Share on other sites More sharing options...
Steven P Posted January 31 Share Posted January 31 So, words are better, can describe why.... An arc is just a part of a circle so make circles first and then arcs afterwards that way you are not concerned with arc lengths initially. The red line is a tangent to the arc you want. If you offset the red line by 400 as a temporary line and draw a circle, radius 400, anywhere on this it will touch the original line. So draw a temporary line offset from the red one and 400 away. If you want an arc or circle to pass a point, point A, the best way is to draw a temporary circle of the same radius centred on the point you want, A. A circle anywhere on that new circle circumference and of the same radius will pass through point A. So draw a temporary circle, radius 400, centred on A. Temporary line says a 400 circle on that and the original line will be tangent to that. Temporary circle says a 400 circle on that will pass through point A. With luck the temporary line and the circle will intersect at least once. This is the centre of the arc. Draw an arc. Delete the temporary lines. It might be that the temporary circle bisects the temporary line twice, means that there are 2 options for the arc, left and right of the point. Quote Link to comment Share on other sites More sharing options...
basty Posted January 31 Author Share Posted January 31 1 hour ago, Steven P said: So, words are better, can describe why.... An arc is just a part of a circle so make circles first and then arcs afterwards that way you are not concerned with arc lengths initially. The red line is a tangent to the arc you want. If you offset the red line by 400 as a temporary line and draw a circle, radius 400, anywhere on this it will touch the original line. So draw a temporary line offset from the red one and 400 away. If you want an arc or circle to pass a point, point A, the best way is to draw a temporary circle of the same radius centred on the point you want, A. A circle anywhere on that new circle circumference and of the same radius will pass through point A. So draw a temporary circle, radius 400, centred on A. Temporary line says a 400 circle on that and the original line will be tangent to that. Temporary circle says a 400 circle on that will pass through point A. With luck the temporary line and the circle will intersect at least once. This is the centre of the arc. Draw an arc. Delete the temporary lines. It might be that the temporary circle bisects the temporary line twice, means that there are 2 options for the arc, left and right of the point. I am at this step (see attached image please). Can you tell me please what to do next? Quote Link to comment Share on other sites More sharing options...
Steven P Posted January 31 Share Posted January 31 (edited) The next step is to draw an arc, using the first option to choose the centre of the arc and make this point the intersection with the the new circle and the offset line. start of the arc will be point A and then (with or without holding down control for direction) pick another point on the first line. If it doesn't quite meet then extend the arc to the line Delete the temporary lines. Before deleting temporary lines you should have something like this: and noting that there are 2 options for the arc. Magenta lines are the temporary construction lines that you have drawn, red + in a circle are the intersections for the centre of the arc. Edited January 31 by Steven P Quote Link to comment Share on other sites More sharing options...
basty Posted February 1 Author Share Posted February 1 It works! Thank you so much Mr. Steven P. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.