# How to move vector onto a curve at a specified point

I have the following code:

ParametricPlot3D[{3*Cos[t]/5, Sin[t], 4*Cos[t]/5}, {t, 0, 2 π}]
data = {{0.55, -0.38, 0.74}, {4/5, 0, -3/5}, {-.23, -.92, -.31}};
Graphics3D[Arrow[{{0, 0, 0}, #}] & /@ data]


I need to combine these two 3D sketchs, the parametric curve and the vectors.

I want to put these three vectors on the {3*Cos[t]/5, Sin[t], 4*Cos[t]/5}, parametric curve at a certain point; i.e., at the parameter t = π/2.

• The Show command can combine 3D graphics objects. – John McGee Mar 31 '17 at 18:41
• Welcome to Mathematica.SE! I suggest the following: 1) As you receive help, try to give it too, by answering questions in your area of expertise. 2) Take the tour! 3) When you see good questions and answers, vote them up by clicking the gray triangles, because the credibility of the system is based on the reputation gained by users sharing their knowledge. Also, please remember to accept the answer, if any, that solves your problem, by clicking the checkmark sign! – Michael E2 Mar 31 '17 at 19:01
• You can format inline code and code blocks by selecting the code and clicking the {} button above the edit window. The edit window help button ? is useful for learning how to format your questions and answers. You may also find this meta Q&A helpful – Michael E2 Mar 31 '17 at 19:01

## 1 Answer

Maybe you are looking for

f[t_] := {3*Cos[t]/5, Sin[t], 4*Cos[t]/5}
v0 = f[π/2];
data = {{0.55, -0.38, 0.74}, {4/5, 0, -3/5}, {-.23, -.92, -.31}};
Show[
ParametricPlot3D[f[t], {t, 0, 2 \[Pi]}],
Graphics3D[Arrow[{v0, #}] & /@ data],
PlotRange -> All]


• You are only great! Maybe a little change but it's very difficult for me (i don't know the program really). Thank you very much.. – deniz Apr 3 '17 at 13:01