How to use a compass to take the distance between two points and use it elsewhere?

WojWoj shared this question 4 years ago

Hello

I have two points A and B ad would like to use the compass to:

• take the distance between points A and B
• make an arc with the center in a point C and a radius of the previous distance [AB]

I do not want to measure that distance (and have it in, say, centimeters) but to construct the arc based on the compass spread (sorry if this is not the right expression, I mean to use the compass to take unitless lengths between points).

Is this possible? (I am sure that it is as this is a fairly basic use for "ruler and compass" kind of constructions)

Thank you for any pointers!

1

Write in the input line:

Circle[C,Distance[A,B]]

You wrote that you want an arc. Therefore you need of cause the information, where the arc starts and where it do stop.

1

I have uploaded a picture to make my question more clear:

I want to place D so that it is at distance [AB] of C ((AB) // (CD)). I used your solution to draw the circle and it places the point D at the intersection between the circle and c1. The only thing is that I do not need the whole circle, only a small arc near the intersection (= near D) - thus my question about the arc.

Is there a way to use one of the tools as if I would be using a compass, that is to take a distance ([AB] in my case) and the click on the center of the arc (C) and place two points to draw the arc (as I would do it with the Arc tool, but having the radius locked)? (in other words, to use the Arc to show the construction lines)

EDIT: I managed to do that through some manipulations but I hope there is a simpler way, one where I actually construct D with the arc:

• draw the whole circle
• draw an Arc with the center in C and two points on the circle (near D)
• go to the properties of the circle and hide it

The result is visually correct but I would prefer to construct the point D directly via the Arc (and not hide the circle and create an artificial arc)

1

Maybe you would like this way:)

Build a compass:

https://www.geogebra.org/m/KUX4NGm7