On which quadrants are each of the six inverse trig functions defined?

In summary, the inverse trigonometric functions can be defined as functions with specific ranges of values. The inverse sin, cos, tan, cotangent, secant, and cosecant functions all have specific ranges of values that define their functionality.
  • #1
smashbrohamme
97
1
I have researched this area a little bit and now I am a little worried because three different websites have gave me three different answers. Some functions matched, but others didn't.

My general consensus is
inverse Sin= 1 and 4 quad
inverse Cos= 1 and 2 quad
inverse tan= 1 and 4 quad
inverse cotangent = 1 and 2 quad
inverse secant= 1 and 2 quad
inverse cosecant= 1 and 4 quad

More importantly is there a quick way to verify this in your calculator?

I tried giving random angles for the inverse functions in my calculator to the so called undefined quadrants for the directed inverse functions but I am not getting a light bulb here.

So maybe a little help?
 
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  • #2
Your quadrants for the respective functions are correct, but just remember that arcsec isn't defined at [itex]\pi/2[/itex], and similarly for arccosec.

These are the principal values of the respective inverse functions. Meaning, for any x, arcsin(x) will definitely give you an answer in [itex](-\pi/2, \pi/2)[/itex] (it is the range for the function). It could also give an answer other other than this range, but then the function itself wouldn't be defined as you need to have a unique element in the range satisfying x. The quadrants you wrote are chosen to be the principle ranges, to define the inverse trigonometric functions.
 
  • #3
can you give me an example on how to prove this?

I am having a hard time grasping this.
 
  • #4
smashbrohamme said:
can you give me an example on how to prove this?

I am having a hard time grasping this.

Prove what? :confused:

As I said, those above principle values were chosen to be the ranges, as they give values for every x. This was done to define the inverse function as functions cannot be have multiple values for the same x.

Read through this to get a better idea.
http://oakroadsystems.com/twt/inverse.htm
 
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Related to On which quadrants are each of the six inverse trig functions defined?

1. What are the six inverse trig functions?

The six inverse trig functions are arcsine (sin^-1), arccosine (cos^-1), arctangent (tan^-1), arccosecant (csc^-1), arcsecant (sec^-1), and arccotangent (cot^-1).

2. What is the definition of the inverse trig functions?

The inverse trig functions are the inverse of their respective trigonometric functions. For example, arcsine is the inverse of sine, and arccosine is the inverse of cosine.

3. What are the quadrants in trigonometry?

The quadrants in trigonometry refer to the four regions created by the x-axis and y-axis on a coordinate plane. They are labeled as the first quadrant, second quadrant, third quadrant, and fourth quadrant.

4. On which quadrants are the inverse trig functions defined?

The inverse trig functions are defined on specific quadrants based on the range of their respective trigonometric functions. Arcsine and arccosecant are defined in quadrants I and IV, arccosine and arcsecant are defined in quadrants I and II, and arctangent and arccotangent are defined in quadrants I and IV.

5. Why is it important to know on which quadrants the inverse trig functions are defined?

It is important to know on which quadrants the inverse trig functions are defined because it affects the values of their outputs. For example, the range of arcsine is limited to -pi/2 to pi/2, so it is only defined in quadrants I and IV, where the sine function is positive. This knowledge is crucial in solving trigonometric equations and applications in mathematics and other fields.

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