A=a^6*a^4; a=a^10=(0,2)^10= -5.12*10^-7
X-y=1
xy=6
x=y+1
y(y+1)=6
x=y+1
y^2+y-6=0
x=y+1
y^2+3y-2y-6=0
x=y+1
y(y+3)-2(y+3)=0
x=y+1
(y-2)(y+3)=0
x=y+1
y=2
y=-3
y=2
x=3
y=-3
x=-2
<em>cos125=cos(180-55)=-cos55</em>
<em>cos85=cos(90-5)=sin5</em>
<span><em>-cos55cos5+sin55sin5=-(cos55cos5-sin55sin5)=-(cos60)=-1/2</em></span>