Question 826871
The graph of the sine function depicts a periodic function which is not 1-1 unless we restrict the domain where the function is 1-1, the restriction is on the interval [-pi/2, pi/2] where pi is 180 degrees.  Note that the x-axis is in radians (i.e. there are 2pi radians in a circle, 90 degrees is pi/2 radians)

{{{ graph( 300, 200, -2.0, 2.0, -2, 2, sin(x) ) }}}

We see that the graph of y = arcsin x is 1-1 over [-1, 1], y axis is in radians

{{{ graph( 300, 200, -2.0, 2.0, -2.5, 2.5, asin(x) ) }}}