02_03_ex_36.tex

{$f(x)=-2\cos x$ at $x=\pi/4$
}
{Tangent line: $y = \sqrt{2}(x-\frac{\pi}{4})-\sqrt{2}$

Normal line: $y = \frac{-1}{\sqrt{2}}(x-\frac{\pi}{4})-\sqrt{2}$
}