# how to draw part of conic?

bostonquad shared this question 6 years ago

Hello,

How can I draw part of a conic, such as a parabola? I need to show the parabola only from its vertex to an intersecting line segment.

Thanks!

1

It's fine to use a y=... notation to define a conic c, so you can use the conics related tools on it, e.g. V=Vertex[c], but you need to use a functional notation to define a part of that conic.

Let's say your conic is y=3x^2+2x-1

and you want to restrict it to a certain interval, e.g. all its points between the x-coordinate of the previously determined vertex V and the x-coordinate of a previously defined point C.

In the input bar, type

f(x)=3x^2+2x-1, x(V)<=x<=x(C)

Now hide the "full" conic by clicking on its visibility marble in Algebra view.

Please note that in Algebra view the two curves you just drew are respectively classified as a conic and a function.

This is major difference in GeoGebra: conics and functions have their reserved tools, so, depending on your goals, you will choose the one or the other notation.

https://ggbm.at/569447

1

Ah, great! Thanks! :D