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Inscribe ellipse in triangle


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Posted

I'm trying to find a way to inscribe an ellipse into a triangle (not an equilateral triangle), i.e. the ellipse touches the 3 inside sides of the triangle.

 

Does anyone know how to do this?

Posted

Inscribing a circle into a triangle has an unique solution, but I would think that an ellipse would have too many variables to be able to offer a general solution.

 

If the ellipse size is fixed then it is easier to draw a triangle to enclose the ellipse, by using the Tangent Osnap.

 

Perhaps if you had some definite sizes in mind, please post them and someone might find a solution.

Posted

Attach what you have tried so far.

Are you familiar with geometry constraints?

Tangent.png

Posted

I don't have a specific example to show you, but I'm looking for a general way to do it. I'm relatively new to autocad since I'm a student learning at the moment. My lecturer was talking about using projection lines and true shapes to draw the ellipses which got me thinking: there must be an easier way to do it, right?

 

@JD Mather: is it possible with geometric constraints? I'm not familiar with it...

 

Thanks for both your help :)

Posted

@JD Mather: is it possible with geometric constraints? I'm not familiar with it...

 

Uhmmm, can't you see the picture? Drag any of the lines and the ellipse updates to remain tangent.

 

Ask your lecturer to show you how to use geometry constraints on the Parametric tab.

 

So Easy!

 

I think a bit more information would be needed though on the design intent.

Posted

There are an infinite number of ellipses that can be tangent to any triangle. Your lecturer should demonstrate the desired solution for this particular problem.

Posted (edited)

Of course, if you just want to draw an ellipse inside a triangle, first draw a circle inside the triangle, and then rotate3d, about any 2point axis to suit :D

 

even though the circle will still be a circle, but it will look like an ellipse.

 

P.S. If you now flatten this rotated circle, it changes into an ellipse

EllipseInTriangle.jpg

Edited by eldon
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