One of the reason why I did not choose to major in math in university was that when I was in senior high school, I can't find any practical application of high school math . As far as I could remember, the topics of math we learnt in high schools were Matrices, Exponent, Logarithm,Differentials Integral, Trigonometry, Sequence, Combinatorics, Composite function,etc. In my opinion, math taught in high school was very theoretic, but less practical. So, I have been wondering this question.

What are the practical application of each topic of mathematics?.

I have listed topics of math that I know. But of course, there are many math topics math that is not mentioned here. my question is not limited to the topics that I managed to mentioned here. The question is addressed to all mathematical topics, including those that are not mentioned in this posting.

What is/are The practical application (s) of trigonometry ?

What is/are the practical application(s) of Calculus?

What is/are the practical application(s) of Algebra ?

What is/are the practical application(s) of Geometry?

What is/are the practical application(s) of Matrices ?

What is/are the practical application(s) of Set Theory?

What is/are the practical application(s) of Logarithm ?