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How to get the expression of the projection of a 3D circle on xOyPlane.

Nicholasfox shared this question 2 years ago

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How to get the expression of the projection of a 3D circle on xOyPlane?

I've tried locusequation command but faild.

please help.

Best Answer

Michael Borcherds ● 2 years ago

I'm sure there's a nicer way, but this works

Sequence((x(Point(c, i)), y(Point(c, i))), i, 0, 0.9, 0.2)
Conic(Element(l1, 1),Element(l1, 2),Element(l1, 3),Element(l1, 4),Element(l1, 5))

Comments (7)

Michael Borcherds ● 2 years ago ●

I'm sure there's a nicer way, but this works

Sequence((x(Point(c, i)), y(Point(c, i))), i, 0, 0.9, 0.2)
Conic(Element(l1, 1),Element(l1, 2),Element(l1, 3),Element(l1, 4),Element(l1, 5))

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Nicholasfox ● 2 years ago

Unbelievable! Thank you very much.

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mathmagic ● 2 years ago

I do not know if nicer way

m1 = {{1, 0, 0}, {0, 1, 0}, {0, 0, 0}}

ApplyMatrix(m1, c)

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Nicholasfox ● 2 years ago

Thanks.

Is there a easy way to transform Parametric equations into Conic equations.

from:

to:

/AQqnOIAMxUaAAAAAAElFTkSuQmCC

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mathmagic ● 2 years ago

only the michael method. create five points and use conic tool

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mathmagic ● 2 years ago

he hecho varios intentos pero siempre se produce un objeto en 3D y para tener una conica hay que reducirlo a 2D usando coordenadas x e y

Files: foro.ggb

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Nicholasfox ● 2 years ago

Have a lesson, thanks.

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