<span>ab+a=a(b+1).
cy-c=c(y-1).
-ma-a=-a(m+1).</span>
2sinαcosα+sin4α=sin2α+sin4α=sin2α+2sin2αcos2α=sin2α(1+2cos2α)
1) sin(3Pi/2-a) = -cosa = -0,8
2) sin210-cos120+tg225 = sin(180+30)-cos(90+30)+tg(180+45) = -sin30+sin30+tg45 = tg45 = 1
tg(α-пи/2)=-tg(пи/2-α)=-ctgα