... = cos^2a + sin^2a - sina * cosa * sina / cosa = cos^2a + sin^2a -sin^2a = cos^2a
возможно уравнение такое:
Log2 ( (sinα+cosα)²-1-1\2sin2α)²+1\4cos²2α)=log2 ((sin²α+2sinα·cosα+cos²α-
-1\2sin2α)²+1\4cos²2α= log2 (1\4sin²2α+1\4cos²2α)=log2 (1\4(sin²2α+cos²2α)=log2 1\4=-2
<B=<D. .......................
(a² -25) /(2a² +10a) =(a -5)(a +5) /2a(a +5) =(a -5) /2a,
при а =0