GeometricLocusMidpoints::usage="Find the geometric locus of the midpoints of the segments of length 5, one end of which describes the line y = 0, z = 0 and the other end, the line z = 3, y = 2x.References: Usunáriz Balanzategui, Ubaldo et al. Problemas de Geometría Analítica y Diferencial. p.230; Personal.";
Development:
Be the extreme points of the segment {a, 0 , 0} y {b, 2b, 3}:
In[]:=
M
a+b
2
,b,
3
2
;b=y;​​Solve
a+y
2
==x,a
{{a2x-y}};
In[]:=
2

2
(a-b)
+
2
(0-2b)
+
2
(0-3)

==25;​​a=2x-y;b=y;​​
2
(a-b)
+4
2
b
-16==0
In[]:=
Expand[-16+
2
(2x-2y)
+4
2
y
0]
Out[]=
-16+4
2
x
-8xy+8
2
y
0
-4+
2
x
-2xy+2
2
y
==0;z==
3
2
;
In[]:=
a1=1;b1=-2;c1=2;​​Indicador==
2
b1
-4a1c1
Indicador-4;
It is an ellipse in space:
Its parametric equations are:
φ[x_]:=x,
2x+
32-4
2
x
4
,
3
2
;​​
φ
1
[x_]:=x,
2x-
32-4
2
x
4
,
3
2
;​​
Graph :
In[]:=
​​ManipulateClearAll;φ[x_]:=x,
2x+
32-4
2
x
4
,
3
2
;
φ
1
[x_]:=x,
2x-
32-4
2
x
4
,
3
2
;
ζ
1
[x_]:=2x-
2x+
32-4
2
x
4
,0,0;
ζ
2
[x_]:=
2x+
32-4
2
x
4
,2
2x+
32-4
2
x
4
,3;​​
ζ
3
[x_]:=2x-
2x-
32-4
2
x
4
,0,0;
ζ
4
[x_]:=
2x-
32-4
2
x
4
,2
2x-
32-4
2
x
4
,3;​​p=Grid[{{{
x
1
,
y
1
,
z
1
},{
x
2
,
y
2
,
z
2
},LongitudeSegment1},{
ζ
1
[t1],
ζ
2
[t1],Norm[
ζ
1
[t1]-
ζ
2
[t1]]}},FrameAll,ItemSize->15,ItemStyle->15];​​q=Grid[{{{
x
3
,
y
3
,
z
3
},{
x
4
,
y
4
,
z
4
},LongitudeSegment2},{
ζ
3
[t1],
ζ
4
[t1],Norm[
ζ
3
[t1]-
ζ
4
[t1]]}},FrameAll,ItemSize->15,ItemStyle->15];​​ShowParametricPlot3D[φ[x],x,-2
2
,t1,PlotStyle->{Blue,Thick}],ParametricPlot3D[
φ
1
[x],x,-2
2
,t1,PlotStyle->{Blue,Thick}],ParametricPlot3D[
ζ
1
[x],x,-2
2
,t1,PlotStyle->{Black,Thick}],​​ParametricPlot3D[
ζ
2
[x],x,-2
2
,t1,PlotStyle->{Black,Thick}],Graphics3D[{Red,Ball[φ[t1],0.09]}],Graphics3D[{Black,Ball[
ζ
1
[t1],0.09]}],Graphics3D[{Black,Ball[
ζ
2
[t1],0.09]}],​​ParametricPlot3D
ζ
3
[x],x,-2
2
,t1,PlotStyle->{Black,Thick},​​ParametricPlot3D[
ζ
4
[x],x,-2
2
,t1,PlotStyle->{Black,Thick}],​​Graphics3D[{Red,Ball[
φ
1
[t1],0.09]}],Graphics3D[{Black,Ball[
ζ
3
[t1],0.09]}],Graphics3D[{Black,Ball[
ζ
4
[t1],0.09]}],Graphics3D[{Black,Thick,Dashed,Line[{
ζ
1
[t1],
ζ
2
[t1]}]}],Graphics3D[{Black,Thick,Dashed,Line[{
ζ
3
[t1],
ζ
4
[t1]}]}]​​,AxesLabel->(Style[#,15,Blue]&/@{"X","Y","Z"}),AxesOrigin{0,0,0},AxesTrue,BoxedFalse,BoxRatiosAutomatic,PlotRange5,ViewPoint{-3,3,2},ImageSize900,Style["Geometric locus of the midpoint of segment:",Bold,Large],{t1,-2.828426,"Value (t1)"},-2
2
+0.00000001,2
2
-0.00000001,0.01,Delimiter,{{p,2,"First segment data"}},Delimiter,{{q,2,"Second segment data"}},ControlPlacementTop
Out[]=
​
Geometric locus of the midpoint of segment:
Value (t1)
First segment data
{
x
1
,
y
1
,
z
1
}
{
x
2
,
y
2
,
z
2
}
LongitudeSegment1
{4.24252,0,0}
{1.41433,2.82866,3}
5.
Second segment data
{
x
3
,
y
3
,
z
3
}
{
x
4
,
y
4
,
z
4
}
LongitudeSegment2
{4.24276,0,0}
{1.41409,2.82819,3}
5.
​