1. The directrix line of a conic.

2. Select the directrix of the new conic...

3. The coastline is the base directrix divides the region of sea and land management.

4. The pity is that the first auxiliary directrix after modification is generally expressed in an algebraic form, because of the complexity of the vectorial expression.

5. Do some research to find the name of this conic and the how the words vertices, foci, centre and directrix relate to this shape.

6. Based on the geometry characteristics of Bertrand surfaces, the complicated surface conjugation issue can be discussed with their directrix line.

7. Select the conic of which you want to construct the directrix...