Recall the important trigonometric identities:
i) [tex]\sin^2x+\cos^2x=1[/tex]
ii) [tex]\tanx = \frac{\sinx}{\cosx} [/tex].
We want to simplify [tex](1-\sin^2x)\cdot \tanx[/tex].
Since, [tex]\sin^2x+\cos^2x=1[/tex], then [tex]1-\sin^2x=\cos^2x[/tex]. Thus, the expression
[tex](1-\sin^2x)\cdot \tanx[/tex]
becomes
[tex]\displaystyle{ \cos^2x \cdot \frac{\sin x}{cosx} = \cos x \sin x.[/tex]
Answer: [tex] \ sinx \ cosx[/tex], or [tex]\displaystyle{ \frac{\sin2x}{2} [/tex].
