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Last updated on July 16th, 2025

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Derivative of 4sinx

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We use the derivative of 4sin(x), which is 4cos(x), 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 4sin(x) in detail.

Derivative of 4sinx for Vietnamese Students
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What is the Derivative of 4sinx?

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

 

The key concepts are mentioned below:

 

Sine Function: (sin(x) is a basic trigonometric function).

Constant Multiplication Rule: Rule for differentiating 4sin(x) (since it is a constant multiplied by a function).

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

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Derivative of 4sinx Formula

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

 

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

 

The formula applies to all x within the domain of the sine function.

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Proofs of the Derivative of 4sinx

We can derive the derivative of 4sin x 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:

 

  1. By First Principle
  2. Using Chain Rule
  3. Using Product Rule

 

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

 

By First Principle The derivative of 4sin x can be proved using the First Principle, which expresses the derivative as the limit of the difference quotient.

 

To find the derivative of 4sin x using the first principle, we will consider f(x) = 4sin x. Its derivative can be expressed as the following limit. f'(x) = limₕ→₀ [f(x + h) - f(x)] / h … (1)

 

Given that f(x) = 4sin x, we write f(x + h) = 4sin (x + h).

 

Substituting these into equation (1), f'(x) = limₕ→₀ [4sin(x + h) - 4sin x] / h = 4 · limₕ→₀ [sin(x + h) - sin x] / h

 

Using the trigonometric identity sin(A + B) = sinAcosB + cosAsinB, f'(x) = 4 · limₕ→₀ [(sin x cos h + cos x sin h) - sin x] / h = 4 · limₕ→₀ [cos x sin h + (cos h - 1) sin x] / h = 4 · [cos x · limₕ→₀ (sin h)/ h + sin x · limₕ→₀ (cos h - 1)/ h]

 

Using limit formulas, limₕ→₀ (sin h)/ h = 1 and limₕ→₀ (cos h - 1)/ h = 0. f'(x) = 4 · [cos x · 1 + sin x · 0] f'(x) = 4cos x. Hence, proved.

 

Using Chain Rule To prove the differentiation of 4sin x using the chain rule, We use the formula: 4sin x = 4 · sin x Consider y = sin x, So we get, 4sin x = 4y By the chain rule: d/dx (4y) = 4 · d/dx (y) … (1)

 

Let’s substitute y = sin x in equation (1), d/dx (4sin x) = 4 · d/dx (sin x) = 4cos x

 

Using Product Rule We will now prove the derivative of 4sin x using the product rule. The step-by-step process is demonstrated below: Here, we use the formula, 4sin x = 4 · sin x Given that, u = 4 and v = sin x

 

Using the product rule formula: d/dx [u·v] = u'·v + u·v' u' = d/dx (4) = 0. (substitute u = 4) v' = d/dx (sin x) = cos x (substitute v = sin x)

 

Again, use the product rule formula: d/dx (4sin x) = u'·v + u·v'

 

Let’s substitute u = 4, u' = 0, v = sin x, and v' = cos x When we simplify each term: We get, d/dx (4sin x) = 0 · sin x + 4 · cos x Thus: d/dx (4sin x) = 4cos x

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Higher-Order Derivatives of 4sinx

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 4sin(x).

 

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 4sin(x), we generally use f⁽ⁿ⁾(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 the x is π/2, the derivative of 4sin x = 4cos(π/2), which is 0. When the x is 0, the derivative of 4sin x = 4cos(0), which is 4.

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Common Mistakes and How to Avoid Them in Derivatives of 4sinx

Students frequently make mistakes when differentiating 4sin x. 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 simplifying the equation

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Students may forget to simplify the equation, which can lead to incomplete or incorrect results. They often skip steps and directly arrive at the result, especially when solving using the product or chain rule. Ensure that each step is written in order. Students might think it is awkward, but it is important to avoid errors in the process.

Mistake 2

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Ignoring the Constant Factor

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They might not remember that 4sin x has a constant factor of 4. Keep in mind that constants affect the overall derivative. Always ensure the constant is included in the differentiation process.

Mistake 3

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Incorrect use of Chain Rule

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While differentiating functions such as 4sin(2x), students misapply the chain rule. For example: Incorrect differentiation: d/dx (4sin(2x)) = 4cos(2x). Correct application: d/dx (4sin(2x)) = 8cos(2x). To avoid this mistake, remember to apply the chain rule correctly by differentiating the inner function and multiplying by the outer function's derivative.

Mistake 4

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Not writing Constants and Coefficients

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There is a common mistake that students at times forget to multiply the constants placed before sin x. For example, they incorrectly write d/dx (4sin x) = cos x. Students should check the constants in the terms and ensure they are multiplied properly. For example, the correct equation is d/dx (4sin x) = 4cos x.

Mistake 5

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Not Applying the Product Rule

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Students often forget to use the product rule when necessary. This happens when differentiating products involving trigonometric functions. For example: Incorrect: d/dx (4xsin x) = 4cos x. To fix this error, students should divide the functions into parts and apply the product rule. For example, d/dx (4xsin x) = 4xcos x + 4sin x.

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Examples Using the Derivative of 4sinx

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Problem 1

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

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Here, we have f(x) = 4sin x·cos x. Using the product rule, f'(x) = u′v + uv′ In the given equation, u = 4sin x and v = cos x.

 

Let’s differentiate each term, u′= d/dx (4sin x) = 4cos x v′= d/dx (cos x) = -sin x

 

substituting into the given equation, f'(x) = (4cos x)·(cos x) + (4sin x)·(-sin x)

 

Let’s simplify terms to get the final answer, f'(x) = 4cos²x - 4sin²x

 

Thus, the derivative of the specified function is 4cos²x - 4sin²x.

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 water fountain's height is represented by the function y = 4sin(x), where y represents the height of the water at a distance x. If x = π/6 meters, measure the rate of change of the fountain's height.

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We have y = 4sin(x) (height of the water)...(1)

 

Now, we will differentiate the equation (1) Take the derivative 4sin(x): dy/dx = 4cos(x)

 

Given x = π/6

 

(substitute this into the derivative) = 4cos(π/6) Since cos(π/6) = √3/2 dy/dx = 4(√3/2) = 2√3

 

Hence, we get the rate of change of the fountain's height at a distance x = π/6 as 2√3.

Explanation

We find the rate of change of the fountain's height at x = π/6 as 2√3, which means that at a given point, the height of the water rises at a rate of 2√3 meters per meter horizontally.

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Problem 3

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

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The first step is to find the first derivative, dy/dx = 4cos(x)...(1)

 

Now we will differentiate equation (1) to get the second derivative: d²y/dx² = d/dx [4cos(x)] d²y/dx² = -4sin(x)

 

Therefore, the second derivative of the function y = 4sin(x) is -4sin(x).

Explanation

We use the step-by-step process, where we start with the first derivative. We differentiate 4cos(x) to find the second derivative, resulting in -4sin(x).

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Problem 4

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

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Let’s start using the chain rule: Consider y = 4sin²(x) = 4[sin(x)]²

 

To differentiate, we use the chain rule: dy/dx = 8sin(x)·d/dx [sin(x)]

 

Since the derivative of sin(x) is cos(x), dy/dx = 8sin(x)·cos(x)

 

Substituting y = 4sin²(x), d/dx (4sin²(x)) = 8sin(x)·cos(x)

 

Hence proved.

Explanation

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

 

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

 

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

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Problem 5

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

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To differentiate the function, we use the quotient rule: d/dx (4sin x/x) = (d/dx (4sin x)·x - 4sin x·d/dx(x))/x²

 

We will substitute d/dx (4sin x) = 4cos x and d/dx (x) = 1 = (4cos x·x - 4sin x·1)/x² = (4xcos x - 4sin x)/x²

 

Therefore, d/dx (4sin x/x) = (4xcos x - 4sin x)/x²

Explanation

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

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FAQs on the Derivative of 4sinx

1.Find the derivative of 4sin x.

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

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

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

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

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Professor Greenline from BrightChamps

Important Glossaries for the Derivative of 4sinx

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

 

  • Sine Function: The sine function is one of the primary trigonometric functions, represented as sin x.

 

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

 

  • Constant Multiplication Rule: A differentiation rule stating that the derivative of a constant times a function is the constant times the derivative of the function.

 

  • Chain Rule: A rule for differentiating compositions of functions, used especially when differentiating products or powers of 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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