二次曲面
椭球面¶
\[
\frac{x^2}{a^2} + \frac{y^2}{b^2} + \frac{z^2}{c^2} = 1
\]
单叶双曲面¶
\[
\frac{x^2}{a^2} + \frac{y^2}{b^2} - \frac{z^2}{c^2} = 1
\]
双叶双曲面¶
\[
- \frac{x^2}{a^2} - \frac{y^2}{b^2} + \frac{z^2}{c^2} = 1
\]
椭圆抛物面¶
\[
z = \frac{x^2}{a^2} + \frac{y^2}{b^2}
\]
双曲抛物面¶
\[
z = - \frac{x^2}{a^2} + \frac{y^2}{b^2}
\]
