$Sin(x+y)= sinxcosy+cosxsiny$
$sin(x-y)= sinxcosy-cosxsiny$
$cos(x+y)= cosxcosy-sinxsiny$
$cos(x-y)= cosxcosy+sinxsiny$
$tan(x+y)= (tanx+tany) / (1-tanxtany)$
$tan(x-y)= (tanx-tany) / (1+tanxtany)$
![[Maths.excalidraw]]
![[Maths Activity.excalidraw]]