A continuous bijection from $l_2 $ onto a subset of $l_2$ whose inverse is everywhere discontinuous.
$\cos(\theta_n) \to \cos(\theta)$ and $\sin(\theta_n) \to \sin(\theta)$. How to show that $\theta_n \to \theta$?
Find the area lying inside the cardioid $r=1+\cos\theta$ and outside the parabola $r(1+ \cos\theta)=1$
Does fundamental group distinguish between any two non homeomorphic topological space?