If then prove that is also equal to y.

As we have to prove:

Given,

y =

As we need to get (1 – cos α + sin α) in numerator, so we need to bring this term in numerator.

∴ Multiplying numerator and denominator by

(1 – cos α + sin α),we get -

using (a + b) (a-b) = a² – b², we get:

∵ 1 – cos²α = sin² α

Thus,