Macchine Matematiche

  • Increase font size
  • Default font size
  • Decrease font size

Tool drawing an ellipse by means of an antiparallelogram


An atiparallelogram linkage is an articulated quadrilateral ABCD where the opposite sides, AB and CD, are the non-parallel sides of an isosceles trapezoid; the remaining two side, AD and BC, are the diagonals of the same trapezoid.

If the antiparallelogram is placed on a plane p, one of the two shortest sides (for example AB) blocked and side AD moved on the plane, it can easily be inferred that C and D describe two circumferences with centers in A and B respectively. Sides AD and BC cross in P.

Because P belongs to the axis of symmetry of the antiparallelogram it is PA + PB = PA + PD = AD = cost. Therefore the set of points described by P is an ellipse with A and B as focal points.

Explore the macchine

 

Hystorical sources

e-mail us

JEvents Calendar

July 2019
S M T W T F S
30 1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30 31 1 2 3

Login