Q. Show that if curvature K(t) of a regular curve γ(t) is >0 every where, then k(t) is a smooth function of t. Give an example to show that this may not be the case without the assumption that k>0.
Let X be a metric space, let K be a closed subset of X, and let x be in X-K. Prove that there exist disjoint open sets U and V such that U contains x and V contains K.