Domain of y=sqrt(cosx): 1st & 4th Quadrant of Unit Circle

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SUMMARY

The domain of the function y = sqrt(cos(x)) is defined mathematically as D = {x | x ∈ [ (4n-1)π/2, (4n+1)π/2 ]}, where n is any integer. This indicates that the valid x-values lie within the intervals corresponding to the first and fourth quadrants of the unit circle, where cos(x) is non-negative. For x values greater than 0, the domain is specifically (0, 1), as negative values of x yield imaginary results due to the square root of negative numbers.

PREREQUISITES
  • Understanding of trigonometric functions, specifically cosine.
  • Knowledge of the unit circle and its quadrants.
  • Familiarity with mathematical notation for expressing domains.
  • Basic concepts of real and imaginary numbers.
NEXT STEPS
  • Research the properties of the cosine function and its graph.
  • Study the unit circle and its significance in trigonometry.
  • Learn about the implications of square roots in real versus imaginary numbers.
  • Explore mathematical notation for defining domains in functions.
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Mathematics students, educators, and anyone interested in understanding the properties of trigonometric functions and their domains.

Calixto
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What would the domain of y = sqrt(cosx) be in mathematical terms. I know that it is all the reals that lie in the first and fourth quadrant of the unit circle, but how would you express that in mathematical terms?
 
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Something like
[tex]D=\{x|x\in[\frac{(4n-1)\pi}{2},\frac{(4n+1)\pi}{2}]\}[/tex]
where n is any integer
 
You first need to define the domain of x.
If x is +60 for example then cos(x)>0 but if it is -60, then it is <0. sqrt of that is an imaginary number which is not defined.

So basically for x>0 domain is (0,1)

I would like to know how Calixto got his answer as I may be wrong.
 

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