Why??

I was going through Play with graphs.

There the graph of \sin^{-1} sinx is given .

Though the graph happens to be okay.
I got one problem.
IT SUGGESTS students to learn defination of it

like
x+2Î ; -5Î /2<= x<= -3Î /2
-Î -x ; -3Î /2<=x<= -Î /2

y=\sin^{-1} sinx = x ; - Î /2<=x<=Î /2
Î -x ; Î /2<=x<=3Î /2
and so on.

My doubt is how are we getting this particular defination.
Please help

4 Answers

1
rohna ·

sorry who?

1
kamalendu ghosh ·

dekh eibhabe inverse trigonometry r sums koris....(doing these after a loong time so pardon me if am wrong)....

case I:
sine-1sine(x)=x ;-∩/2≤x≤∩/2

case II
when Î /2<=x<=3Î /2

add or subtract suitably so that we bring a region within -∩/2 and∩/2....

here let us subtract -∩...

-∩/2≤x-∩≤∩/2 but sine(x-∩)=-sinx so we instead multiply by -1 andtake..
-∩/2≤∩-x≤∩/2 check sine (∩-x)=sinx

case III:

-5Î /2<= x<= -3Î /2

add 2∩
-∩/2≤x+2∩≤∩/2 sine(x+2pi)=sine x

1
kamalendu ghosh ·

case IV

-3Î /2<=x<= -Î /2
add pi...

we get -.5 pi≤x+pi≤.5pi

but then sine(x+pi)=-sine x

so we multiply both sides by -1
-.5pi≤-x-pi≤.5x

49
Subhomoy Bakshi ·

yo kamalendu da! :D

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