What is the relationship between the sides and angles of a triangle?

Well, to begin with the two sides were co-habiting the space quite happily, until the hypotenuse moved in and began pushing the two sides apart as it took up more and more space. The angle between the two originally happy sides became more and more obtuse, with acute insults being fired between the original sides and the hypotenuse. Eventually Pythagoras stepped in and established a 90° angle between the original lines as part of a court order, while the hypotenuse was fixed evenly between the two lines.

Or perhaps upon a more serious note.

soh cah toa

Sin = opposite/hypotenuse

cos = adjacent/hypotenuse

tan = opposite/adjacent

This however only applies to right angled triangles

For other triangles.

Area = 1/2 ab sin C

a^2 = b^2 + c^2 Where a is the hypotenuse

Sin A / a = Sin B/b = Sin C/c

And I have no clue what any of that means... sorry! lol!