- #1

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- 5

Simplify the expression

$\dfrac{{\cos 2x\ }}{{\cos x-{\sin x\ }\ }}

=\dfrac{{{\cos}^2 x-{{\sin}^2 x\ }\ }}{{\cos x\ }-{\sin x\ }}

=\dfrac{({\cos x}-{\sin x})({\cos x}+{\sin x\ })}{{\cos x}-{\sin x}}

=\cos x +\sin x$

ok spent an hour just to get this and still not sure

suggestions?