Always helps to remember these.
Take a right angle triangle, with sides labelled ‘a’, ‘b’, and ‘c’.
Using the identities, we can then replace with sin, and with cos.
The proof for works best for me visually.
There a few different methods to proove the relationship, this page has a nice summary of several.
We use to represent the area of the larger square. We can calculate A in 2 ways; the area of the large square, or as an addition of the areas of the 4 triangles and the smaller square.tags: math - trigonometry - linearalgebra