Which trigonometric functions have a domain of [tex]$[-1,1]$[/tex]?

A. [tex]$y=\arcsin x$[/tex] and [tex]$y=\arccos x$[/tex]
B. [tex]$y=\arccos x$[/tex] and [tex]$y=\arctan x$[/tex]
C. [tex]$y=\arcsin x$[/tex] and [tex]$y=\arctan x$[/tex]
D. [tex]$y=\operatorname{arcsec} x$[/tex] and [tex]$y=\operatorname{arccsc} x$[/tex]



Answer :

To solve this question, we need to identify which trigonometric functions have a domain of \([-1, 1]\).

Firstly, let's recall the definitions and domains of some common inverse trigonometric functions:

1. \( y = \arcsin x \):
- Definition: This is the inverse function of \( \sin y \).
- Domain: The domain for \( \arcsin x \) is \([-1, 1]\).

2. \( y = \arccos x \):
- Definition: This is the inverse function of \( \cos y \).
- Domain: The domain for \( \arccos x \) is \([-1, 1]\).

3. \( y = \arctan x \):
- Definition: This is the inverse function of \( \tan y \).
- Domain: The domain for \( \arctan x \) is all real numbers \((-\infty, \infty)\).

4. \( y = \operatorname{arcsec} x \):
- Definition: This is the inverse function of \( \sec y \).
- Domain: The domain for \( \operatorname{arcsec} x \) is \( (-\infty, -1] \cup [1, \infty)\).

5. \( y = \operatorname{arccsc} x \):
- Definition: This is the inverse function of \( \csc y \).
- Domain: The domain for \( \operatorname{arccsc} x \) is \( (-\infty, -1] \cup [1, \infty)\).

Now, we check which of the given pairs have the domain \([-1, 1]\):

1. \( y = \arcsin x \) and \( y = \arccos x \):
- Both \( \arcsin x \) and \( \arccos x \) have the domain \([-1, 1]\).

2. \( y = \arccos x \) and \( y = \arctan x \):
- \( \arccos x \) has the domain \([-1, 1]\), but \( \arctan x \) has the domain \((-\infty, \infty)\).

3. \( y = \arcsin x \) and \( y = \arctan x \):
- \( \arcsin x \) has the domain \([-1, 1]\), but \( \arctan x \) has the domain \((-\infty, \infty)\).

4. \( y = \operatorname{arcsec} x \) and \( y = \operatorname{arccsc} x \):
- Both \( \operatorname{arcsec} x \) and \( \operatorname{arccsc} x \) have the domain \( (-\infty, -1] \cup [1, \infty)\).

The correct functions with the domain \([-1, 1]\) are \( y = \arcsin x \) and \( y = \arccos x \).

Thus, the correct answer is:
[tex]\[ y = \arcsin x \text{ and } y = \arccos x \][/tex].