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Its evident that in the truth table of $p \to q$

When $p$ is False and $q$ is True, Then $p \to q$ is True.

But in some instances i could not convince myself about this truth value.

For example:

$p$: Quadrilateral is Cyclic

$q$: Opposite angles are supplementary

Now is $p$ is False and $q$ is True, how can $p \to q$ can be True?