Sin^2x-cos^2x

is a trig ratio piece

= 1

sin^2 x + cos^2 x = 1

but
since cos (2x) = cos^2 x - sin^2 x

sin^2 x-cos^2 x = - sin(2x)

argggh

meant to say:
sin^2 x - cos^2 x = - cos(2x)

To simplify the expression sin^2x - cos^2x, we can use the identity for the difference of squares:

a^2 - b^2 = (a + b)(a - b)

In this case, a = sinx and b = cosx.

Let's substitute these values into the formula:

(sin^2x - cos^2x) = (sinx + cosx)(sinx - cosx)

So, the simplified expression is (sinx + cosx)(sinx - cosx).