Question

prove that
cos A/(1-sin A) = (1-sin A)/cos A

Answer 1

multiply top and bottom with the conjugate of the denominator(left side)

Answer 2

what is the conjugate of 1-sin a ?

Answer 3

here is an example
the conjugate of a-b is a+b
change the sign in the middle term of two terms

Answer 4

1st) multiply top and bottom with the conjugate of the denominator
2nd) apply the foil method for the denominator
3rd) use the identity sin^2x +cos^2 x=1