21 Aprilis 2017
- 17:0817:08, 21 Aprilis 2017 diff hist +19 Trigonometria →Historia: Marcelius atrado taip: 1-cosx=1+secnx {senas tecstas{1-cosx=x^2/2}
- 17:0017:00, 21 Aprilis 2017 diff hist +197 Trigonometria →Historia: 2011 m Vaduovelyje daiktas [1-COSx~x^2/2 }MARCELIUS ATRADO [ 1-Cosx=1+X