Question

I don't understand how to solve this pls help

Answer 1

the sine function is a many-to-one function and therefore has no inverse function.

However if the domain is restricted to -90° ≤ x ≤ 90°

Then the function is one-to-one for this domain

Thus, $sin^{-1}$ x is defined as the angle such that - π/2 ≤ x ≤ π/2

5π/6 is therefore outwith the domain