let
A---------> the angle
if sin A=-0.4
then
A=sin-1(-0.4)
using a calculator
A=-23.578°--------> the angle A belong to the IV quadrant
convert to radians
if pi radians-----------> 180°
x-------------------> -23.578°
x=-23.578*pi/180--------> x=-0.41 radians
the answer is
-0.41 radians
