Answer:
Step-by-step explanation:
[tex]\tan (x-\frac{\pi }{2} )=\frac{tan~x-tan~\frac{\pi }{2} }{1+tan~x~tan~\frac{\pi }{2} } \\or~\cot(x-\frac{\pi }{2} )=\frac{1+\tan~x~\tan\frac{\pi }{2} }{\tan~x-\tan~\frac{\pi }{2} } \\divide~the~R.H.S. ~by~\tan ~x~\tan~\frac{\pi }{2} \\=\frac{\cot~x~\cot~\frac{\pi }{2} +1 }{\cot~\frac{\pi }{2} -\cot~x} \\\cot\frac{\pi }{2} =0\\\cot(x-\frac{\pi }{2} )=\frac{\cot~x ~\times~0+1}{0-\cot~x} \\\cot~(x-\frac{\pi }{2} )=-\frac{1}{\cot~x} =-\tan~x[/tex]
