[tex]1-sin(2a)=(sin a - cos a)^2[/tex]
1-sin(2a); sin(2a) = 2sin(a)cos(a)
1-2cos(a)sin(a); 1 = [tex]sin^2a + cos^2a[/tex]
[tex]cos^2 a -2cos(a)sin(a)+sin^2a[/tex]
[tex](sin(a) - cos(a) )^2[/tex]
[tex]=\ \textgreater \ (sin(a) - cos(a))^2 = (sin(a)-cos(a))^2 -Adevarat[/tex]