IIT JEE , AIEEE Forum - Mathematics , Trignometry

Decoder

here is another way..

look..1 + sinA is nothing but [cosA/2 + sinA/2 ]² ..

so.

1+ sinA = / cosA/2 + sinA/2 / .... ( / is modulus)..

1 - sinA = / cosA/2 - sinA/2 /..

u open these modulus by applying simple logic ..

that when and how...for wat values of A/2.. inside mod values r positive...

ur main focus must be on "-" wala mod..

u have to get 2cosA/2..

thus u want minus wala mod to be opened as -- cosA/2 - sinA/2...

this can happen only wen cosA/2 > sinA/2.. (as mod values we want to be positive)..

so this happens wen A/2 [-/4,/4]..

so so A [-/2,/2]..