Is there any way to change a straight line to an arc with a specific central angle once drawn?

# Changing a line to an arc

**gadget2020**#2

not once drawn, but you can use the line for ‘snap to’ points for a new arc, then delete it.

**jhardiman72**#3

Thanks. I can’t seem to find the right arc tool for the information I have. I only have the central angle, which is 72.56 degrees. I need to draw an arc that ends at two specific points with that angle. I do not have the radius or the arc length. Any ideas?

**gadget2020**#5

I would draw a line from the mid point of the line you’ve just drawn, perpendicular to it towards the inside of the arc. I would then rotate a copy of it by 36.28º and move that rotated line to snap to the end point of the initial line. The intersection of the perpendicular line and the rotated line is the centre of the arc/circle.

**jhardiman72**#6

I’m not sure that I need the center of the arc. Here is what I have so far:

The first (complete) arc has a central angle of 72.56 degrees. The length of that arc is 104’. There is a 12" distance between both arcs, and the drawings that I’m going off of do not have the length or any other measurement for the back arc. I need to draw it in segments, but I can’t seem to match the angle without the radius or overall length.

Find the center as @gadget2020 showed. Create construction lines from there through the two endpoints of the first segment of your arc and through the final endpoint (you can create a construction line at some easy angle through the center and rotate copies to hit endpoints of arc segments). Draw the outer line the required distance from the first arc segment (your figure looks like you may already have done this). Now rotate+copy the new segment about the arc center so that its end reaches the third construction line above. Then type /n (where n is the number of segments in your original arc).

Of course, once you know the center you can draw a second arc with the required radius…I was just having fun following the course you started on…

**gadget2020**#8

for the outside radius I would just offset rather than having to draw another curve (or segment)