prove that inA-cosA+1÷sinA+cosA-1=1÷secA-tanA using identity sec2A = 1+tan2A
(sin A-cos A+1)/(sin A+cosA-1)=1/(sec A-tan A)
L.H.S. divide above and below by cos A
=(tan A-1+secA)/(tan A+1-sec A)
=(tan A-1+secA)/(1-sec A+tan A)
We know that 1+tan^2(A)=sec ^2(A)
Or put in deminator 1=sec^2(A)-tan ^2(A)=(sec A+tan A)(secA-tanA)
=(sec A+tan A-1)/[(sec A+tan A)(sec A-tan A)-(sec A-tan A)]
=(sec A+tan A-1)/(sec A-tan A)(sec A+tan A-1)
= 1/(sec A-tan A) , proved.
LHS =RHS