A zero vector can have many directions, but only you deserve the length, just as I have many friends, but only you deserve my protection.

Ours is a circle because its eccentricity is 0.

3. I think you are a bad decimal, stubborn over and over again.

4. We are parabolas, you are the focus and I am the line of sight. I'll know how deep you think I am.

5. My love for you is like a monotonically increasing unbounded function.

6. Life is a calculus equation. Meeting you that day proved that the solution in my life exists and is unique.

7. There is a happy saying in mathematics: if we combine similar items, we all wear the same school uniform, so we are similar items.