# The observation of the coreset in K-median clustering problems [duplicate]

I have seen two observations from the paper by Har-Peled but I do not know how to prove them (i) If $$C1$$ and $$C2$$ are the $$(k, ε)$$-coresets for disjoint sets P1 and P2 respectively, then $$C1 ∪ C2$$ is a $$(k, ε)$$-coreset for $$P1 ∪ P2$$. (ii) If $$C1$$ is $$(k, ε)$$-coreset for $$C2$$, and $$C2$$ is a$$(k, δ)$$-coreset for $$C3$$, then $$C1$$ is a $$(k, ε+δ)$$- coreset for $$C3$$

Can anyone please figure it out?