The output is the angle
The input is the trig function
An inverse sine of 1/2 is the angle 30 degrees
sine of 30 is 1/2
arcsin(1/2) = 30 degrees
arcsine, inverse sine and sin-1 are all the inverse of sine
the sine of 30 is the input, 30 is the output

Katie B.
Looks good! To get more specific, I would say that the input is the trig ratio. In Raymond's example using sine, 1/2 represents the ratio opposite/hypotenuse.03/23/20