I'm interested in showing that $CX=\frac{I\times X}{\{1\}\times X}$ is contractible.
I defined the d.r $F(s,[t,x])=[(1-s)t+s,x]$ and the only missing part for me is to show that it is continuous. How do I do that?
I did see some related questions (example: J. J. Rotman's proof that the cone is contractible ), but couldn't understand completly why $F$ is continuous iff $F\circ(q×1)$ is continuous.
Also, is there a more traditional way to show the continuity?
Thanks