Teşekkürler
X=sin220−cos2201−sin40=(sin20−cos20)(sin20+cos20)sin220+cos220−2.sin20.cos20=(sin20−cos20)(sin20+cos20)(sin20−cos20)2=sin20+cos20sin20−cos20
X.sin20−X.cos20=sin20+cos20
(X−1)sin20=(X+1)cos20
sin20cos20=tan20=X+1X−1