Find dy/dx implicitly and find the largest interval of the form −a < y < a or 0 < y < a such that y is a differentiable function of x. cos y = x

Respuesta :

Answer:

dy/dx = -1/√(1 - x²)

For 0 < y < π

Step-by-step explanation:

Given the function cos y = x

-siny dy = dx

-siny dy/dx = 1

dy/dx = -1/siny (equation 1)

But cos²y + sin²y = 1

=> sin²y = 1 - cos²y

=> siny = √(1 - cos²y) (equation 2)

Again, we know that

cosy = x

=> cos²y = x² (equation 3)

Using (equation 3) in (equation 2), we have

siny = √(1 - x²) (equation 4)

Finally, using (equation 4) in (equation 1), we have

dy/dx = -1/√(1 - x²)

The largest interval is when

√(1 - x²) = 0

=> 1 - x² = 0

=> x² = 1

=> x = ±1

So, the interval is

-1 < x < 1

arccos(1) < y < arxcos(-1)

= 0 < y < π

The required value is,

[tex]\frac{dy}{dx}=-\frac{1}{siny}[/tex]

Differentiation:

Differentiation, in calculus, can be applied to measure the function per unit change in the independent variable.

It is given that,

[tex]cos y=x[/tex]

Now, differentiating the function with respect to [tex]x[/tex].

[tex]-siny \frac{dy}{dx} =1\\\frac{dy}{dx}=-\frac{1}{siny}[/tex]

We have to find the largest interval so that [tex]y[/tex] is a differentiable function [tex]x[/tex]Then,

[tex]\frac{dy}{dx}=-\frac{1}{siny}[/tex]

The function[tex]\frac{1}{siny}[/tex] is defined only if [tex]siny\neq 0[/tex]

Therefore [tex]y\neq n \pi[/tex]  where [tex]n \in \mathbb{Z}[/tex]

Then,[tex]-n \pi[/tex]

Hence, the function is a differentiable function of [tex]x[/tex] if [tex]-n \pi[/tex]

Learn more about the topic differentiation:

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