New Help, Cannot Seem to Get it

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SUMMARY

The derivative of the inverse cosine function, arccos(x), is proven to be -1/(Sqrt(1-x^2)). This is established by differentiating the identity cos(arccos(x)) = x. By letting y = arccos(x) and applying implicit differentiation, the relationship dx/dy = -sin(y) leads to dy/dx = -1/sin(y). Utilizing trigonometric identities and right triangle properties further simplifies the expression to the final derivative.

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  • Understanding of inverse trigonometric functions
  • Knowledge of implicit differentiation techniques
  • Familiarity with trigonometric identities
  • Basic concepts of right triangle geometry
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  • Study implicit differentiation in calculus
  • Learn about trigonometric identities and their applications
  • Explore the properties of inverse trigonometric functions
  • Practice problems involving derivatives of inverse functions
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Students studying calculus, particularly those focusing on differentiation of inverse trigonometric functions, as well as educators seeking to clarify these concepts for their students.

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Prove that (d/dx)arcos(x) = -1/(Sqrt(1-x^2)


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cos is the inverse function of arccos. So cos(arccos(x))=x. Differentiate both sides. Did you try that?
 
Or: if y= arccos(x) then x= cos(y). Differentiate that to find dx/dy= -sin(y) so that
dy/dx= -1/sin(y)= -1/sin(arccos(y)).

Use trig identities to simplify that (change sin(arccos(y)) to cos(arccos(y))=y) or think about a right triangle with "near side" of length y and hypotenuse of length 1. What is the length of the "opposite side"? Whatr is the sine?
 

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