Respuesta :

secx = 1/cosx
cot x = 1/tanx
1 + tan^2(x) = sec^2(x)
minus tan^2(x) on both sides,
1 = sec^2(x) - tan^2(x)

sec(x)/cos(x) - tan(x)/cot(x)
=1/cos^2(x) - tan^2(x)
= sec^2(x) - tan^2(x)
= 1