# How to create arc between 3 points

Hey all,

I’m new to the live components thing, I just wanted to see if someone could help me figure out (if possible), how to create an arc between 3 points using Trimble Creator?

Thanks!

Actually don’t worry think i figured it out by using the circle node and finding the circumradius of the ‘triangle’ created by the 3 points.

Or at least i’m on the right path, but something needs fixing (supposed to be a complete circle:

Good morning
I’m interested to see your graph for calculating the radius of the circumcircle of the triangle.
See which calculation method you have opted for to calculate the center of the circle. THANKS

Good morning
I managed to find the center of the circle with the centroid method. It remains to find the correct angles for the beginning and end of the circle.
I hesitate to calculate the total angle and then do a rotation.
The angle between node returns the lowest value and not necessarily the correct one, we will have to calculate the normal and then do a test on the dot product to know if we take the angle or 180-the angle.
But that’s for tomorrow.

https://creator.trimble.com/graph?assetURI=whp:a9b18836-331f-4d84-8781-010ae8c9fa85 Hello
https://creator.trimble.com/graph?assetURI=whp:a8e4b65c-86cf-4300-9b55-a5dbda231f21

Some configurations still need to be corrected by adding tests
For now, works for points ABC where A is the furthest point from the origin.
For the moment, the transformation of the circle only takes into account the rotation around the Z axis in the case of 3 points belonging to a plane parallel to the XY plane.

A little help to improve! Gday

I simplified my calcs down, as one of the 3 points I need the arc drawn through was evenly spaced in the x plane I found I could use the formula here: Art of Problem Solving .
As point 2 for me was evenly spaced between, it formed a nice right angled triangle that i could use to calculate everything from and work out the angles using trig. (note. snip below is only using a curve between points, I’m yet to ‘bugfix’ my other method)

I had a quick look at your component and it looks great . Streets ahead of where i’m currently up to! I will have to investigate the centroid method.

1 Like

Can anyone help me why this formula won’t work in the expression node?
`(a*b*c)/sqrt((a+b+c)*(b+c-a)*(c+a-b)*(a+b-c))`

it returns “insufficient operands (+,-,*,…_) in formula”
Upon removing the brackets inside the sqrt formular to this: `(a*b*c)/sqrt(a+b+c*b+c-a*c+a-b*a+b-c)`
I get this: "invalid string operation: / "

Is there a wiki or some documentation for this that goes through everything?

Cheers