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Last updated on September 27, 2025

Derivative of Sin 4x

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We use the derivative of sin(4x), which is 4cos(4x), as a measuring tool for how the sine function changes in response to a slight change in x. Derivatives help us calculate profit or loss in real-life situations. We will now talk about the derivative of sin(4x) in detail.

Derivative of Sin 4x for US Students
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What is the Derivative of Sin 4x?

We now understand the derivative of sin 4x. It is commonly represented as d/dx (sin 4x) or (sin 4x)', and its value is 4cos(4x). The function sin 4x has a clearly defined derivative, indicating it is differentiable within its domain.

 

The key concepts are mentioned below:

 

Sine Function: (sin(x)).

 

Chain Rule: Rule for differentiating sin(4x) due to the multiplication of the angle by a constant.

 

Cosine Function: cos(x) is the derivative of sin(x).

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Derivative of Sin 4x Formula

The derivative of sin 4x can be denoted as d/dx (sin 4x) or (sin 4x)'.

 

The formula we use to differentiate sin 4x is: d/dx (sin 4x) = 4cos(4x)

 

The formula applies to all x.

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Proofs of the Derivative of Sin 4x

We can derive the derivative of sin 4x using proofs. To show this, we will use the trigonometric identities along with the rules of differentiation.

 

There are several methods we use to prove this, such as:

 

  • By First Principle
     
  • Using Chain Rule
     
  • Using Product Rule

 

We will now demonstrate that the differentiation of sin 4x results in 4cos(4x) using the above-mentioned methods:

 

By First Principle

 

The derivative of sin 4x can be proved using the First Principle, which expresses the derivative as the limit of the difference quotient. To find the derivative of sin 4x using the first principle, we will consider f(x) = sin 4x. Its derivative can be expressed as the following limit. f'(x) = limₕ→₀ [f(x + h) - f(x)] / h … (1) Given that f(x) = sin 4x, we write f(x + h) = sin (4(x + h)). Substituting these into equation (1), f'(x) = limₕ→₀ [sin(4(x + h)) - sin(4x)] / h = limₕ→₀ [2cos(4x + 2h) sin(2h)] / h Using the limit formula, limₕ→₀ (sin h)/h = 1, f'(x) = 4cos(4x) Hence, proved.

 

Using Chain Rule

 

To prove the differentiation of sin 4x using the chain rule, We use the formula: If y = sin u, where u = 4x, then dy/dx = dy/du * du/dx dy/dx = cos(4x) * 4 Thus, dy/dx = 4cos(4x)

 

Using Product Rule

 

Although not typically used for sine functions, the product rule can be applied in creative ways to differentiate sin 4x if the function is broken into parts. For simplicity, the chain rule remains the best approach for this function.

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Higher-Order Derivatives of Sin 4x

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 sin(4x).

 

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 sin(4x), we generally use fⁿ(x) for the nth derivative of a function f(x) which tells us the change in the rate of change (continuing for higher-order derivatives).

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Special Cases:

When x is a multiple of π/4, the derivative takes specific values depending on the quadrant.

 

When x is 0, the derivative of sin 4x = 4cos(0), which is 4.

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Common Mistakes and How to Avoid Them in Derivatives of Sin 4x

Students frequently make mistakes when differentiating sin 4x. These mistakes can be resolved by understanding the proper solutions. Here are a few common mistakes and ways to solve them:

Mistake 1

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Not applying the Chain Rule

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Students may forget to apply the chain rule, which is crucial when differentiating functions like sin 4x. They might differentiate it as cos(x) instead of 4cos(4x).

 

Always remember to include the derivative of the inner function (4x in this case).

Mistake 2

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Incorrectly Simplifying Trigonometric Identities

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While working with derivatives, students may incorrectly simplify trigonometric identities, leading to wrong results.

 

Ensure that trigonometric identities are applied correctly, and check every step for accuracy.

Mistake 3

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Mixing Up Derivative and Integral

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Students sometimes confuse the differentiation process with integration. For instance, they might integrate instead of differentiate.

 

Always double-check whether the task is to differentiate or integrate.

Mistake 4

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Ignoring the Coefficient in the Angle

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There is a common mistake where students forget to multiply the derivative of the angle. For example, they might write d/dx (sin 4x) = cos(4x) instead of 4cos(4x).

 

Always include the derivative of the inner function.

Mistake 5

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Misplacing Parentheses

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Errors occur when parentheses are misplaced, leading to incorrect expressions.

 

Ensure that parentheses are correctly placed to avoid errors in the differentiation process.

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Examples Using the Derivative of Sin 4x

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Problem 1

Calculate the derivative of sin(4x)cos(x).

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Here, we have f(x) = sin(4x)cos(x). Using the product rule, f'(x) = u′v + uv′ In the given equation, u = sin(4x) and v = cos(x). Let’s differentiate each term, u′ = d/dx (sin(4x)) = 4cos(4x) v′ = d/dx (cos(x)) = -sin(x) Substituting into the given equation, f'(x) = (4cos(4x))(cos(x)) + (sin(4x))(-sin(x)) Let’s simplify terms to get the final answer, f'(x) = 4cos(4x)cos(x) - sin(4x)sin(x) Thus, the derivative of the specified function is 4cos(4x)cos(x) - sin(4x)sin(x).

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.

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Problem 2

A clock's pendulum swings in a pattern described by the function y = sin(4x), where y represents the height at time x. If x = π/8 seconds, determine the rate of change of the pendulum's height.

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We have y = sin(4x) (height of the pendulum)...(1) Now, we will differentiate the equation (1) Take the derivative sin(4x): dy/dx = 4cos(4x) Given x = π/8, substitute this into the derivative: 4cos(4(π/8)) = 4cos(π/2) 4 * 0 = 0 (since cos(π/2) = 0) Hence, the rate of change of the pendulum's height at x = π/8 is 0.

Explanation

We find the rate of change of the pendulum's height at x = π/8 as 0, which means that at this point, the height of the pendulum is at a maximum or minimum, and the rate of change is zero.

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Problem 3

Derive the second derivative of the function y = sin(4x).

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The first step is to find the first derivative, dy/dx = 4cos(4x)...(1) Now we will differentiate equation (1) to get the second derivative: d²y/dx² = d/dx [4cos(4x)] Here we use the chain rule, d²y/dx² = 4 * (-sin(4x)) * 4 = -16sin(4x) Therefore, the second derivative of the function y = sin(4x) is -16sin(4x).

Explanation

We use the step-by-step process, where we start with the first derivative.

Using the chain rule, we differentiate 4cos(4x).

We then substitute the identity and simplify the terms to find the final answer.

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Problem 4

Prove: d/dx (sin²(4x)) = 8sin(4x)cos(4x).

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Let’s start using the chain rule: Consider y = sin²(4x) = [sin(4x)]² To differentiate, we use the chain rule: dy/dx = 2sin(4x). d/dx [sin(4x)] Since the derivative of sin(4x) is 4cos(4x), dy/dx = 2sin(4x) * 4cos(4x) = 8sin(4x)cos(4x) Hence proved.

Explanation

In this step-by-step process, we used the chain rule to differentiate the equation.

Then, we replace sin(4x) with its derivative.

As a final step, we substitute y = sin²(4x) to derive the equation.

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Problem 5

Solve: d/dx (sin(4x)/x)

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To differentiate the function, we use the quotient rule: d/dx (sin(4x)/x) = (d/dx (sin(4x)) * x - sin(4x) * d/dx(x))/ x² We will substitute d/dx (sin(4x)) = 4cos(4x) and d/dx (x) = 1 = (4cos(4x) * x - sin(4x) * 1) / x² = (4xcos(4x) - sin(4x)) / x² Therefore, d/dx (sin(4x)/x) = (4xcos(4x) - sin(4x)) / 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.

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FAQs on the Derivative of Sin 4x

1.Find the derivative of sin 4x.

Using the chain rule for sin 4x, d/dx (sin 4x) = 4cos(4x) (simplified)

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2.Can we use the derivative of sin 4x in real life?

Yes, we can use the derivative of sin 4x in real life in calculating the rate of change of any motion, especially in fields such as mathematics, physics, and engineering.

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3.Is it possible to take the derivative of sin 4x at the point where x = π/2?

Yes, it is possible to take the derivative at x = π/2, as sin 4x is defined for all real numbers.

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4.What rule is used to differentiate sin(4x)/x?

We use the quotient rule to differentiate sin(4x)/x, d/dx (sin(4x)/x) = (4xcos(4x) - sin(4x))/x².

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5.Are the derivatives of sin 4x and sin⁻¹x the same?

No, they are different. The derivative of sin 4x is equal to 4cos(4x), while the derivative of sin⁻¹x is 1/√(1-x²).

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6.Can we find the derivative of the sin 4x formula?

To find, consider y = sin 4x. Using the chain rule: y’ = cos(4x) * 4 = 4cos(4x).

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Important Glossaries for the Derivative of Sin 4x

  • Derivative: The derivative of a function indicates how the given function changes in response to a slight change in x.

 

  • Sine Function: A trigonometric function represented as sin(x), indicating the y-coordinate of a point on the unit circle.

 

  • Cosine Function: A trigonometric function represented as cos(x), which is the derivative of the sine function.

 

  • Chain Rule: A rule used in calculus for differentiating compositions of functions.

 

  • Product Rule: A calculus rule used to find the derivative of the product of two functions.
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Jaskaran Singh Saluja

About the Author

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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Fun Fact

: He loves to play the quiz with kids through algebra to make kids love it.

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