calculus
posted by Adc .
Verify the identity:
cos x cox x/1tan x = sin x cos x/sin x cos x

LS = cosx = cosx/(1  sinx/cosx))
= cosx  cosx/(cosx  sinx)/cosx) )
= cosx  cosx (cosx)/(cosx  sinx)
= cosx + cos^2 x /(sinx  cosx)
= (sinxcosx  cos^2 x + cos^2 x)/(sinx  cosx)
= sinxcosx/(sinx  cosx)
= RS