load (draw)$

winkelvektor(v) := block ([],
      atan(v[2]/v[1]) / (2*%pi)*360
    );

p1 : [1,1]$
a : [4,3]$
b : [2,5]$
a : [5,2]$
b : [2,4]$
alpha : winkelvektor(a);
beta : winkelvektor(b);

laq : a . a, vector_simp;
la : sqrt (laq);
ab : a . b, vector_simp;

p2 : p1 + b;

/* Projektionspunkt */
F : p1 + ab/laq * a;

delta1 : winkelvektor (p1+b - F) + 180;

p4 : F +
     0.3 * 
     [cos ((delta1 + 45)/360*2*%pi), 
      sin ((delta1 + 45)/360*2*%pi)
     ]
     ; 

ta : p1 + a + [0.2, -0.2];
text1 : concat ("set label '{/=25 @_{/=25 a}^{/=15 ->}}' at ", ta[1], "," , ta[2]);
tb : p1 + b + [0.2, +0.2];
text2 : concat ("set label '{/=25 @_{/=25 b}^{/=15 ->}}' at ", tb[1], "," , tb[2]);
tc : (p1 + (F - p1)/2 + [0, -0.5]), numer;
text3 : concat ("set label '{/=25 | @_{/=25 b}^{/=15 ->} | cos ({/Symbol g})}' at ", tc[1], "," , tc[2], " enhanced");

draw2d (
  xtics = false, ytics = false,
  xaxis = false, yaxis = false,
  xrange = [0,7],
  yrange = [0,7],
  head_length = 0.2,
  vector (p1,a),
  vector (p1,b),
  points_joined = true,
  point_type = none,
  line_type = dots,
  points ([p2, F]),
  user_preamble = [
        "set noborder",
        "set label '{/Symbol g}' at 1.4, 1.45 enhanced",
        text1, text2, text3
        ],
  transparent = true,
  line_type = solid,
  ellipse (p1[1], p1[2], 1.0, 1.0, beta, alpha-beta),
  point_type = filled_circle,
  point_size = 1,
  points([p4]),
  ellipse (F[1], F[2], 0.5, 0.5, delta1, 90),
       
   file_name = "projektion",
   dimensions = [600,600],
   terminal = eps
);