Question

cos^2x-sinxcosx-sin^2x

Answer 1

Are you certain this is entirely accurate? (Speaking primarily about the second subtraction, before sin^2x)

Answer 2

i dont think so that you stated it rightly..............

Answer 3

cos^2x = sin^2x + sinxcosx

1= sin^2x/cos^2x + sinxcosx / cos^2x
1 = tan^2x + sinx / cosx
1= tan^2x + tanx
jsut played with it ^^