What is the domain of sin(arcsin(x))?

  • Thread starter Thread starter 11thHeaven
  • Start date Start date
  • Tags Tags
    Domain
Click For Summary
SUMMARY

The domain of the function sin(arcsin(x)) is defined as x ∈ [-1, 1]. This is because arcsin(x) is only defined for x values within this interval, as the arcsine function is the inverse of the restricted sine function, which is one-to-one when limited to the domain of [-π/2, π/2]. Although sine has all real numbers as its domain, the output of arcsin(x) restricts the input for sin(arcsin(x)) to the interval [-1, 1]. Thus, the domain of sin(arcsin(x)) is directly tied to the domain of arcsin(x).

PREREQUISITES
  • Understanding of inverse functions, specifically sine and arcsine
  • Knowledge of the domain and range of trigonometric functions
  • Familiarity with the concept of one-to-one functions
  • Basic knowledge of function restrictions in mathematics
NEXT STEPS
  • Study the properties of inverse functions in trigonometry
  • Learn about the restrictions applied to the sine function to create the arcsine function
  • Explore the domain and range of other trigonometric functions
  • Investigate the implications of function restrictions on their inverses
USEFUL FOR

Students studying trigonometry, mathematicians exploring inverse functions, and educators teaching concepts related to function domains and ranges.

11thHeaven
Messages
48
Reaction score
0

Homework Statement


I need to find the domain of sin(arcsin(x)). Now I "know" that this is xε(-1,1), but I don't understand why. If the range of arcsin(x) is (-∏/2,∏/2), then shouldn't this be the domain of sin(arcsin(x))?

Help appreciated.
 
Physics news on Phys.org
sin (arcsin(x)) means that first arcsin is applied to x, then the result of that is passed on to sin. In what set must x be for this to make sense?
 
Since sine has all real numbers as domain, the domain of this function is the domain of arcsine. Do you understand why its domain is [-1, 1]?
 
HallsofIvy said:
Since sine has all real numbers as domain, the domain of this function is the domain of arcsine. Do you understand why its domain is [-1, 1]?

I understand why the domain of arcsin is [1,-1]. But if sine is the inverse of arcsine, shouldn't the domain of sine be the range of arcsine? I thought that was the rule where inverse functions are concerned.
 
11thHeaven said:
I understand why the domain of arcsin is [1,-1]. But if sine is the inverse of arcsine, shouldn't the domain of sine be the range of arcsine? I thought that was the rule where inverse functions are concerned.
The sine function is not a one-to-one function, so technically, there is no function which is the inverse of sine function.

So, where do we get the arcsine function from? If we restrict the sine function to a domain of [-π/2, π/2], then that restricted sine function is one-to-one. (By the Way: The range of this restricted sine function is [-1, 1], the same as for the "unrestricted" sine function.) The arcsine function is the inverse of this restricted sine function.

As it turns out, sin(arcsin(x)) has the same domain and range regardless of which of these sine functions is used.
 

Similar threads

  • · Replies 105 ·
4
Replies
105
Views
7K
Replies
16
Views
2K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 20 ·
Replies
20
Views
3K
Replies
2
Views
1K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K