the sines and cosines of any angle is always between -1 and 1
the inverse functions are arcsinx and arccosx
inverses switch x and y coordinates
if (x,y) is a point on one function, (y,x) is a point on the inverse function
if the range of sinx and cosx is -1 to 1
then the domain of arcsinx and arccosx is -1 to 1
switching x and y is the same as switching range and domain
a is correct