What do we know for certain and how do we know it?

There are different ways in which one can know things for certain and ways in which one can prove such statement.

Ways of knowing: Reason, language, emotion, imagination, perception, faith, memory and intuition.

Areas of knowledge: Mathematics, arts, natural sciences, human sciences, ethics and history.

Some examples that fit this would be  that, I know my friend plays football because I have reason to know that he does. This would fit one of the ways of knowing. I know that the square of the hypotenuse of a right triangle is equal to the sum of the squares of the two other sides, I know this due to it being proven my mathematics. This fits as one of the areas of knowledge.

The problem that is encountered here, is, how credible are the sources in which/who we get and learn all our information from? the ones that cant just be proven mathematically or because you have experienced it yourself. T.O.K would be the subject to analyze more in depth into discussions like these and really dig into the way we know everything that we have learned. One example i personally used to think it was true when i was a kid, was that if you don't go to sleep before midnight then a ghost will come into your room, but after many late night binge watching series or doing school work, i can confirm it is false.. or at least for now.