Recall, $$\pi$$ is defined as the ratio of the circumference (say c) of a circle to its diameter (say d). That is, $$\pi$$=c/d. This seems to contradict the fact that $$\pi$$ is irrational. How will you resolve this contradiction?

Though $$\pi$$ =$$\frac{c}{d}$$, it is an approximate value. As we get an approximate value and not a fixed one, there is no contradiction. Mathematically,
$$\frac{c}{d}$$=$$\frac{2 \pi r}{2r}$$=$$\pi$$.