Derivative of e^cosx
2026-02-28 09:05 Diff
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Last updated on October 3, 2025

We use the derivative of e^cosx, which involves the chain rule, as a tool to understand how the function changes in response to a slight change in x. Derivatives help us calculate profit or loss in real-life situations. We will now discuss the derivative of e^cosx in detail.

What is the Derivative of e^cosx?

We now understand the derivative of e^cosx. It is commonly represented as d/dx (e^cosx) or (e^cosx)', and its value is -sin(x)·ecosx.

The function ecosx has a clearly defined derivative, indicating it is differentiable within its domain. The key concepts are mentioned below:

Exponential Function: ex, where e is a constant approximately equal to 2.71828.

Chain Rule: Rule for differentiating composite functions.

Cosine Function: cos(x) is a trigonometric function.

Derivative of e^cosx Formula

The derivative of ecosx can be denoted as d/dx (ecosx) or (ecosx)'.

The formula we use to differentiate e^cosx is: d/dx (ecosx) = -sin(x)·ecosx

The formula applies to all x within the domain of cos(x).

Proofs of the Derivative of e^cosx

We can derive the derivative of e^cosx using proofs. To show this, we will use the chain rule along with the rules of differentiation. There are several methods we use to prove this, such as:

  1. By Using Chain Rule
  2. Using the properties of exponential functions
  3. Using Chain Rule

To prove the differentiation of e^cosx using the chain rule, We use the formula: f(x) = e^u(x), where u(x) = cos(x)


The derivative f'(x)  is \( e^u(x)·u'(x). \)

Let’s substitute u(x) = cos(x) and find u'(x) = -sin(x). Thus, f'(x) = e^cosx·(-sin(x)) = -sin(x)·e^cosx

Hence, proved.

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Higher-Order Derivatives of e^cosx

When a function is differentiated several times, the derivatives obtained are referred to as higher-order derivatives. Higher-order derivatives can be a little tricky.

To understand them better, think of a car where the speed changes (first derivative) and the rate at which the speed changes (second derivative) also changes. Higher-order derivatives make it easier to understand functions like e^cosx.

For the first derivative of a function, we write f′(x), which indicates how the function changes or its slope at a certain point. The second derivative is derived from the first derivative, which is denoted using f′′(x). Similarly, the third derivative, f′′′(x), is the result of the second derivative, and this pattern continues.

For the nth Derivative of e^cosx, we generally use fⁿ(x) for the nth derivative of a function f(x), which tells us the change in the rate of change.

Special Cases:

When x is π, the derivative is zero because sin(π) = 0. When x is 0, the derivative of e^cosx = -sin(0)·e^1, which is 0.

Common Mistakes and How to Avoid Them in Derivatives of e^cosx

Students frequently make mistakes when differentiating e^cosx. These mistakes can be resolved by understanding the proper solutions. Here are a few common mistakes and ways to solve them:

Problem 1

Calculate the derivative of (e^cosx·sinx)

Okay, lets begin

Here, we have f(x) = e^cosx·sinx. Using the product rule, f'(x) = u′v + uv′ In the given equation, u = e^cosx and v = sinx.

Let’s differentiate each term, u′ = d/dx (e^cosx) = -sin(x)·e^cosx v′ = d/dx (sinx) = cosx

Substituting into the given equation, f'(x) = (-sin(x)·e^cosx)·(sinx) + (e^cosx)·(cosx)

Let’s simplify terms to get the final answer, f'(x) = -sin^2(x)·e^cosx + cosx·e^cosx

Thus, the derivative of the specified function is e^cosx(cosx - sin^2x).

Explanation

We find the derivative of the given function by dividing the function into two parts. The first step is finding its derivative and then combining them using the product rule to get the final result.

Well explained 👍

Problem 2

A company observes that the output of a machine follows the function y = e^cosx, where y represents output and x represents time in hours. If x = π/3 hours, determine the rate of change of output.

Okay, lets begin

We have y = e^cosx (output function)...(1)

Now, we will differentiate the equation (1)

Take the derivative of e^cosx: dy/dx = -sin(x)·e^cosx

Given x = π/3 (substitute this into the derivative)

dy/dx = -sin(π/3)·e^cos(π/3) = -√3/2·e^(1/2)

Hence, we get the rate of change of output at x = π/3 hours as -√3/2·e^(1/2).

Explanation

We find the rate of change of output at x = π/3 by substituting the value of x into the derivative. This gives us the rate at which the output is changing at that specific time.

Well explained 👍

Problem 3

Derive the second derivative of the function y = e^cosx.

Okay, lets begin

The first step is to find the first derivative, dy/dx = -sin(x)·e^cosx...(1)

Now we will differentiate equation (1) to get the second derivative: d²y/dx² = d/dx [-sin(x)·e^cosx]

Here we use the product rule, d²y/dx² = [-cos(x)·e^cosx]·(-sin(x)) + [-sin(x)]·[-sin(x)·e^cosx] = cos(x)·sin(x)·e^cosx + sin²(x)·e^cosx

Therefore, the second derivative of the function y = e^cosx is e^cosx[sin²(x) + cos(x)·sin(x)].

Explanation

We use the step-by-step process, where we start with the first derivative. Using the product rule, we differentiate each component. We then substitute the derived identities and simplify the terms to find the final answer.

Well explained 👍

Problem 4

Prove: d/dx (e^cos²x) = -2sin(x)cos(x)e^cos²x.

Okay, lets begin

Let’s start using the chain rule: Consider y = e^cos²x = e^(cos(x)²)

To differentiate, we use the chain rule: dy/dx = e^u(x)·u'(x), where u(x) = cos(x)² u'(x) = 2cos(x)·(-sin(x))

Thus, dy/dx = e^cos²x·[-2sin(x)cos(x)] = -2sin(x)cos(x)e^cos²x Hence proved.

Explanation

In this step-by-step process, we used the chain rule to differentiate the equation. We identified the inner function and its derivative, then substituted back to derive the equation.

Well explained 👍

Problem 5

Solve: d/dx (e^cosx/x)

Okay, lets begin

To differentiate the function, we use the quotient rule: d/dx (e^cosx/x) = (d/dx (e^cosx)·x - e^cosx·d/dx(x))/x²

We will substitute d/dx (e^cosx) = -sin(x)·e^cosx and d/dx (x) = 1 = ([-sin(x)·e^cosx]·x - e^cosx·1)/x² = (-x·sin(x)·e^cosx - e^cosx)/x² = -e^cosx(x·sin(x) + 1)/x²

Therefore, d/dx (e^cosx/x) = -e^cosx(x·sin(x) + 1)/x².

Explanation

In this process, we differentiate the given function using the quotient rule. As a final step, we simplify the equation to obtain the final result.

Well explained 👍

FAQs on the Derivative of e^cosx

1.Find the derivative of e^cosx.

Using the chain rule for e^cosx involves differentiating the inner function: d/dx (e^cosx) = -sin(x)·e^cosx

2.Can we use the derivative of e^cosx in real life?

Yes, we can use the derivative of e^cosx in real life to calculate the rate of change in various fields such as physics and engineering, where systems exhibit exponential and trigonometric behavior.

3.Is it possible to take the derivative of e^cosx at the point where x = π/2?

Yes, it is possible to take the derivative at x = π/2 because e^cosx is defined there, and its derivative is -sin(π/2)·e^cos(π/2) = -e^0 = -1.

4.What rule is used to differentiate e^cosx/x?

We use the quotient rule to differentiate e^cosx/x: d/dx (e^cosx/x) = (-sin(x)·e^cosx·x - e^cosx)/x².

5.Are the derivatives of e^cosx and e^-cosx the same?

No, they are different. The derivative of e^cosx is -sin(x)·e^cosx, while the derivative of e^-cosx is sin(x)·e^-cosx.

6.Can we find the derivative of the e^cosx formula?

To find, consider y = e^cosx. Using the chain rule, the derivative is: y' = e^cosx·(-sin(x)) = -sin(x)·e^cosx.

Important Glossaries for the Derivative of e^cosx

  • Derivative: The derivative of a function indicates how the given function changes in response to a slight change in x.
  • Exponential Function: A function in which a constant base is raised to a variable exponent, commonly written as e^x.
  • Chain Rule: A rule used in calculus for differentiating the composition of two or more functions.
  • Trigonometric Function: A function related to angles and ratios, such as sine, cosine, and tangent.
  • Product Rule: A rule used to differentiate products of two functions, written as d/dx [u·v] = u'v + uv'.

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Jaskaran Singh Saluja

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Jaskaran Singh Saluja is a math wizard with nearly three years of experience as a math teacher. His expertise is in algebra, so he can make algebra classes interesting by turning tricky equations into simple puzzles.

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