Note If a conic in $\mathbb{R}P^{2}$ contains a line, then it is degenerate. Theorem. Through five points $P_{1},P_{2},P_{3},P_{4},P_{5} \in \mathbb{R}P^{2}$ there exists a conic in $\mathbb{R}P^{2}$. $i)$ If no four points lie on a line, then the conic is unique. … Continue reading Lecture 13