In fact (sin x)–1 = 
1
sin x  and
similarly for other trigonometric functions ® The value of an inverse trigonometric functions which lies in its principal
value branch is called the principal value of that inverse trigonometric
functions For suitable values of domain, we have
® y = sin–1 x ⇒ x = sin y
® x = sin y  ⇒ y = sin–1 x
® sin (sin–1 x) = x
® sin–1 (sin x) = x
Rationalised 2023-24
INVERSE TRIGONOMETRIC FUNCTIONS     33
Historical Note
The study of trigonometry was first started in India The ancient Indian
Mathematicians, Aryabhata (476A