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Last updated on September 27, 2025
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.
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).
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.
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:
We will now demonstrate that the differentiation of sin 4x results in 4cos(4x) using the above-mentioned methods:
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.
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)
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.
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).
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.
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:
Calculate the derivative of sin(4x)cos(x).
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).
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.
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.
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.
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.
Derive the second derivative of the function y = sin(4x).
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).
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.
Prove: d/dx (sin²(4x)) = 8sin(4x)cos(4x).
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.
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.
Solve: d/dx (sin(4x)/x)
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
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.
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.
: He loves to play the quiz with kids through algebra to make kids love it.