Question

VERIFY:(1-sinx)/(1+sinx)= sec^2x-2secxtanx+sec^2x-1

Answer 1

easy. on the left, multiply by (1-sinx)/(1-sinx)

you get (1-2sinx + sin^2x)/(cos^2x)

which is
sec^2x-2secxsinx/cosx+(1-cos^2x)/cos^2x
which immediately leads to the solution