sin^–1(sin x) = x

Provided x ϵ ≈ [–1.57,1.57]

And in our equation x is 4 which does not lie in the above range.

We know sin[π – x] = sin[–x]

∴ sin(π – 4) = sin(–4)

Also π–4 belongs in

∴ sin^–1(sin 4) = π – 4