@ssara  In your code, instead  _local(cos);  should be  local cos;  and instead  B := op([1, 2], A)*(-cos(theta)+1)+op(2, A);  should be  B:=op([1,2], A)*(1-cos(theta))+op(2, A):  . Just copy the whole code from my answer into your worksheet and check that the codes exactly match. 
Tell me what version of Maple you use and upload here a link to your worksheet using the bold green arrow (the worksheet should be saved before that) if my code does not work again.

@Markiyan Hirnyk  In fact, Maple simply ignores  assuming real . But the solution itself is correct. In terms of  V2  and  V3  we have  V2=0  and  V3=0

Use  Digits  command to get the required number of significant digits:

Example:

Digits:=3:
a:=1.23402*10^(-5);
a*10^6;
                                       a := 0.0000123
                                             12.3
 

@tomleslie  And I prefer that it's shorter (and/or faster). I do not see any reason to use for sets or lists   numelems  instead of  nops. You allude to a wider field of application of  numelems  in comparison with nops . But if we follow this logic, for example it's better to use  `**`  to raise to an exponent than `^` (because a single symbol  `*` can be used for multiplication and exponentiation). Or the area of any plane figure should be calculated by integration (for example, the area of a rectangle than just multiplying its sides).

Even when working with matrices, I prefer other commands than numelems, because it is usually required to know not only the total number of entries in the matrix, but the number of rows and the number of columns. Here is an example:

A:=<1,2,3; 4,5,6>;
m, n:=op(1, A);
`*`(%);
m*n;
numelems(A);
                                                    

@tomleslie The actual number of points may not coincide with numpoints. See help for numpoints and the example. Note that near the origin the points are more often:

plot(abs(x), x=-2..2, style=point, symbol=solidcircle, numpoints=40);

@ssara  Nothing needs to be converted. Just open this file in your Maple.

@ssara  You do not need any for loops. The substitution and collection must be done immediately in the entire matrix. See the corrected file ss_new.mw 

@shimaa sadk  You can easily write these results into a list, and then assign names to them.

Example:

{x=1, y=2, z=3};
L:=eval([x,y,z], %);
a, b, c := op(L);  # The new names (a multiple assignment)

@das1404  I offered you a possible option for Maple 7 here, but it seems you did not read it.

@vv  I already answered this question twice, indicating the explicit formulas here. But for some reason OP does not read his own posts.

@asa12  I do not know what the issue is. In my 32 bit Maple 2015.2 (Windows 10) everything works correctly. Here is the file  Example_animation.mw
See screen-shot:

@asa12  In Maple 2015 everything works correctly. You have initialized the procedure code. And then probably you forgot to execute the following code:

RotationIn2D(2,1);

@das1404  Your calculations are correct, except  hs . For your parameters should be  hs=sqrt(2)/2  rather than  1/2 . In my code first there were 2 errors in the expressions for  st  and  hs  (I took the wrong segments). Now everything is fixed.

@asa12  The blue particle is at the origin. The red particle rotates around the blue one. x0, y0 are the initial coordinates of the red particle:

RotationIn2D:=proc(x0, y0)
local A;
uses plots;
A:=t-><cos(t),-sin(t); sin(t),cos(t)>;
animate(plot, [[[convert(A(s).<x0,y0>,list)[],s=0..t], [convert(A(t).<x0,y0>,list)]], style=[line, point], linestyle=3, color=red, symbol=solidcircle, symbolsize=17], t=0..2*Pi, frames=90,background=plot([[0,0]], style=point, symbol=solidcircle, color=blue, symbolsize=17), axes=none, scaling=constrained); 
end proc:

Example of use:

RotationIn2D(2,1);

Edit.

@Markiyan Hirnyk  Thank you for attention! The reason for the error is that there are just no solutions for these parameters. I made the necessary adjustments to the procedure code. Now it returns an empty list in such cases.

For example 
HeronianTriangles(170, 165);

returns the solutions.