Find the exact value of the expression if possible or enter impossible

Impossible.the expression    would give you an angle that has a cosine ratio of  .if cosine is adjacent over hypotenuse, this would imply that there would be a triangle with a leg measuring  units long and the hypotenuse 1 unit long.the thing is,  which is bigger than 1.the hypotenuse of a right angle triangle has to be greater than the other sides.we cannot have a right-angle triangle with one of the legs 1.4 and the hypotenuse being 1.impossible.

I’m pretty sure it’s i think : /