[tex]sin( \frac{\pi}{2}-x)=sin( \frac{\pi}{2})(cos(x)-cos( \frac{\pi}{2})sin(x)\\
sin( \frac{\pi}{2}-x)=1\times cos(x) -0\times sin(x)\\
\boxed{sin( \frac{\pi}{2}-x)= cos(x)}\\\\
tan( \frac{\pi}{2}-x)= \frac{sin(\frac{\pi}{2}-x)}{cos(\frac{\pi}{2}-x)} \\\\
tan(\frac{\pi}{2}-x)= \frac{cos(x)}{sin(x)}\\\\
tan(\frac{\pi}{2}-x)= \frac{cos(x)}{tan(x)cos(x)} \\\\
\boxed{tan(\frac{\pi}{2}-x)= \frac{1}{tan(x)}} [/tex]