1.

Evaluate each of the following:sin–1(sin4)

Answer»

sin–1(sin x) = x

Provided x ∈ \([\frac{-\pi}2,\frac{\pi}2]\) ≈ [–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 \([\frac{-\pi}2,\frac{\pi}2]\)

∴ sin–1(sin 4) = π – 4

sin-1(sin 3)

As we know that sin-1(sin x) = x with x ∈ [-π/2, π/2] which is approximately equal to [-1.57, 1.57]

But here x = 3, which does not lie on the above range,

So, we know that sin (π – x) = sin (x)

Thus, sin (π – 3) = sin (3)

also π – 3 ∈ [-π/2, π/2]

Sin-1(sin 3) = π – 3


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