Warum istrr cos^-1(1.18) nicht zu errechnen?

$$\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{cos}}^{\!\!\mathtt{-1}}{\left({\mathtt{1.18}}\right)} = \underset{{\tiny{\text{Error: invalid argument}}}}{\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{cos}}^{\!\!\mathtt{-1}}{\left({\mathtt{1.18}}\right)}}$$

$$\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{cos}}^{\!\!\mathtt{-1}}{\left({\mathtt{0}}\right)} = {\mathtt{90^{\circ}}}$$       ;    $$\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{cos}}^{\!\!\mathtt{-1}}{\left({\mathtt{0.5}}\right)} = {\mathtt{60^{\circ}}}$$       ;   $$\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{cos}}^{\!\!\mathtt{-1}}{\left({\mathtt{1}}\right)} = {\mathtt{0^{\circ}}}$$

cos^-1   (arcuscos)   für Werte > 1 nicht definiert !

Gruß radix !

Danke (: