# How to form an inclined arc in cone structure

Hii all…
How to form an inclined arc and how to I give its center height of the arc…Please clarify my doubt…and Guide me…Here by attached the Rhino file video.

Thanking you…

Hi -

I’m not sure what you mean by that. If that’s the radius, just click the `Radius` option, provide the radius and snap to, e.g., the opposite side of the rectangle.
-wim

An arc is a planar object - that is to say it lies in a specific plane. I assume what you want is to create an arc that is not in one of the 3 principal planes. Determining that plane (any plane) requires 3 points - in this case the start and the end of the arc, plus either a center point or a point on the arc in order to fix the plane in which the arc lies. Wherever you snap that third point to will determine this plane.

If you want the arc to lie in a specific plane, and you don’t have an existing reference point for the third input point, you will need to set the active viewport’s CPlane first to that plane. Then, any arc you draw will automatically lie in that plane (assuming the snap points also lie on the plane).

Quite often we have to do some construction to get the result we want in cases like this. Here is one way you can get your arc.

1. Create a 3-point plane from the triangle you want the arc to lie in. Select the two points that are going to be the ends of the arc first, then the opposite apex.

2. Draw a single line whose length is the height of the arc. Start at the mid point of the plane between the ends of the arc. Head towards the mid point on the opposite edge of the plane. When the cursor snaps to the mid point of the second edge, keeping the mouse button pressed down, hit tab to lock in the direction. Then type in the distance you want, hit return and release the mouse button.

3. Draw a 3-point arc, selecting the two end points, then the end of your height line.

4. Delete the plane and height line.

Regards
Jeremy