Construction of Ellipse by Oblong Method (or Rectangular method)

CONSTRUCTION OF ELLIPSE BY OBLONG METHOD (or Rectangular method)

Data known :

1. Major axis 

2. Minor axis

Example 4: 

Construct an ellipse with major axis 100mm and minor axis 80mm by rectangular method.

Procedure:

Draw a rectangular EFGH with length EF equal to major axis (100mm) and width GH equal to minor axis (80mm).

2. Draw major axis AB bisecting the width and minor axis CD bisecting the length. Let the intersecting of major axis and minor axis be the point 'O'.

3. Divide the semi major axis AB into any number of equal parts (say 4) 2' and name the parts as 1, 2 and 3 from A.

4. Divide the semi minor axis AH also into same number of equal parts and name the parts as 1',2' and 3' from A.

5. Draw lines joining 1', 2' and 3' with C.

6. Similarly draw lines joining 1, 2 and 3 with D, to intersect the lines C-1' at P1, C-2' at P2 and C-3' at P3 respectively. 

7. Join the points A, P1, P2, P3 and C by a smooth curve which is the one-quarter of ellipse.

8. Repeating the same procedure for the remaining three quarters, required ellipse can be obtained as shown in Fig. 6.11.