Thread: Deriving addition identities geometrically

I am trying to figure out how to derive the addition formulas using triangles. his is what I came up with so far. Is this on the right track? How do I finish it? I am trying to attach a file, don't know if it will work.

Originally Posted by manyarrows

I am trying to figure out how to derive the addition formulas using triangles. his is what I came up with so far. Is this on the right track? How do I finish it? I am trying to attach a file, don't know if it will work.

Hi manyarrows,

See Section 1.5 here.