Parametric ray intuition

We can parameterize the ray from $C$ through $P$ as a function of $t$: $\qquad R(t) = (1-t)C + tP$ If $R(t) = I$ and we move $I$ towards $C$, then $t$ must [[☃ dropdown 1]]. You can use the interactive diagram below for help: [[☃ iframe 1]]