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Last updated on July 15th, 2025

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Derivative of 2sinxcosx

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We use the derivative of the function 2sinxcosx, which simplifies to sin(2x), to understand how this function changes in response to a slight change in x. Derivatives help us in various real-life applications such as physics and engineering. We will now discuss the derivative of 2sinxcosx in detail.

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What is the Derivative of 2sinxcosx?

We now understand the derivative of 2sinxcosx. This function simplifies to sin(2x), which is differentiable within its domain. The derivative of sin(2x) is commonly represented as d/dx (sin(2x)) or (sin(2x))', and its value is 2cos(2x). The key concepts are mentioned below: - Double Angle Formula: 2sinxcosx = sin(2x). - Derivative of Sine: The derivative of sin(x) is cos(x). - Chain Rule: Rule for differentiating composite functions like sin(2x).

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Derivative of 2sinxcosx Formula

The derivative of 2sinxcosx can be denoted as d/dx (2sinxcosx) or (2sinxcosx)'. The formula we use to differentiate 2sinxcosx, which simplifies to sin(2x), is: \[d/dx (sin(2x)) = 2cos(2x)\] The formula applies to all x within the domain of the cosine function.

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Proofs of the Derivative of 2sinxcosx

We can derive the derivative of 2sinxcosx using proofs. To show this, we will use trigonometric identities along with differentiation rules. Several methods can be used to prove this, such as: - Using the Double Angle Identity - Applying the Chain Rule - Using the Product Rule We will demonstrate that the differentiation of 2sinxcosx results in 2cos(2x) using these methods: Using the Double Angle Identity The function 2sinxcosx can be rewritten using the double angle identity: \[2sinxcosx = sin(2x)\] The derivative of sin(2x) is found using the chain rule: \[d/dx (sin(2x)) = 2cos(2x)\] Applying the Chain Rule To differentiate sin(2x) using the chain rule, let: \[u = 2x\] \[d/dx (sin(u)) = cos(u) \cdot du/dx = cos(2x) \cdot 2 = 2cos(2x)\] Using the Product Rule For the product 2sinxcosx, let: \[u = 2sinx \quad \text{and} \quad v = cosx\] \[d/dx (u \cdot v) = u' \cdot v + u \cdot v'\] \[u' = 2cosx, \quad v' = -sinx\] \[d/dx (2sinxcosx) = 2cosx \cdot cosx + 2sinx \cdot (-sinx)\] \[= 2cos^2x - 2sin^2x = 2(cos^2x - sin^2x) = 2cos(2x)\]

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Higher-Order Derivatives of 2sinxcosx

When a function is differentiated multiple times, the resulting derivatives are referred to as higher-order derivatives. Higher-order derivatives can be complex. For instance, consider 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 analyze functions like 2sinxcosx. For the first derivative of a function, we write f′(x), indicating the function's rate of change or slope at a point. The second derivative is derived from the first derivative, denoted as f′′(x). Similarly, the third derivative, f′′′(x), is derived from the second derivative, and this pattern continues. For the nth Derivative of 2sinxcosx, we use fⁿ(x) to denote the nth derivative of a function f(x), describing the change in the rate of change.

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Special Cases:

At x = π/2, the derivative of 2sinxcosx is 2cos(π) = -2. At x = 0, the derivative of 2sinxcosx = 2cos(0) = 2.

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Common Mistakes and How to Avoid Them in Derivatives of 2sinxcosx

Students frequently make mistakes when differentiating 2sinxcosx. 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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Ignoring the Double Angle Identity

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Students may overlook the double angle identity for 2sinxcosx, which can simplify the differentiation process. Recognize that 2sinxcosx = sin(2x) to make differentiation easier.

Mistake 2

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Forgetting to Apply the Chain Rule

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When differentiating composite functions like sin(2x), students sometimes forget to apply the chain rule. Always differentiate the outer function and multiply by the derivative of the inner function.

Mistake 3

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Incorrect Use of Product Rule

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Differentiating 2sinxcosx directly without considering the double angle identity can lead to errors. Ensure you apply the product rule correctly by identifying each part of the product.

Mistake 4

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Misplacing Constants

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Sometimes, students forget to multiply constants correctly. For instance, they might write the derivative of 2sinxcosx as cos(2x) instead of 2cos(2x). Always check constants and coefficients.

Mistake 5

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Not Recognizing Trigonometric Identities

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Students may not use trigonometric identities effectively, such as cos^2x - sin^2x = cos(2x). Understanding these identities can simplify derivatives significantly.

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Examples Using the Derivative of 2sinxcosx

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Problem 1

Calculate the derivative of (2sinxcosx · e^x)

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Here, we have f(x) = (2sinxcosx) · e^x. Using the product rule, f'(x) = u′v + uv′ In the given equation, u = 2sinxcosx and v = e^x. Let’s differentiate each term, u′ = d/dx (2sinxcosx) = 2cos(2x) v′ = d/dx (e^x) = e^x Substituting into the given equation, f'(x) = (2cos(2x)) · e^x + (2sinxcosx) · e^x Let’s simplify terms to get the final answer, f'(x) = 2e^x (cos(2x) + sinxcosx) Thus, the derivative of the specified function is 2e^x (cos(2x) + sinxcosx).

Explanation

We find the derivative of the given function by dividing it 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 company constructs a bridge with an arch modeled by y = 2sinxcosx. Determine the slope of the bridge at x = π/6 meters.

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We have y = 2sinxcosx (slope of the bridge)...(1) Now, we will differentiate the equation (1) Take the derivative of 2sinxcosx: dy/dx = 2cos(2x) Given x = π/6, substitute this into the derivative: dy/dx = 2cos(π/3) = 2(1/2) = 1 Hence, the slope of the bridge at x = π/6 is 1.

Explanation

We find the slope of the bridge at x = π/6 as 1, which means that at this point, the elevation of the bridge changes at a rate equal to the horizontal distance.

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Problem 3

Derive the second derivative of the function y = 2sinxcosx.

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The first step is to find the first derivative, dy/dx = 2cos(2x)...(1) Now, we will differentiate equation (1) to get the second derivative: d²y/dx² = d/dx [2cos(2x)] Using the chain rule, d²y/dx² = -4sin(2x) Therefore, the second derivative of the function y = 2sinxcosx is -4sin(2x).

Explanation

We use a step-by-step process, starting with the first derivative. Using the chain rule, we differentiate 2cos(2x), substitute the identity, and simplify the terms to find the final answer.

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Problem 4

Prove: d/dx ((2sinxcosx)²) = 8sinxcosxcos(2x).

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

Explanation

In this step-by-step process, we used the chain rule to differentiate the equation. Then, we replaced sin(2x) with its derivative. As a final step, we substituted back to derive the equation.

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Problem 5

Solve: d/dx (2sinxcosx/x)

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To differentiate the function, we use the quotient rule: d/dx (2sinxcosx/x) = (d/dx (2sinxcosx) · x - 2sinxcosx · d/dx(x)) / x² We substitute d/dx (2sinxcosx) = 2cos(2x) and d/dx (x) = 1 = (2cos(2x) · x - 2sinxcosx · 1) / x² = (2xcos(2x) - 2sinxcosx) / x² Therefore, d/dx (2sinxcosx/x) = (2xcos(2x) - 2sinxcosx) / 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 2sinxcosx

1.Find the derivative of 2sinxcosx.

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2.Can we use the derivative of 2sinxcosx in real life?

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

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4.What rule is used to differentiate 2sinxcosx/x?

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5.Are the derivatives of 2sinxcosx and sin(2x) the same?

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Important Glossaries for the Derivative of 2sinxcosx

- Double Angle Identity: A trigonometric identity that expresses 2sinxcosx as sin(2x). - Chain Rule: A rule for differentiating composite functions. - Product Rule: A rule used to differentiate products of two functions. - Sine Function: A primary trigonometric function, expressed as sin(x). - Cosine Function: A primary trigonometric function, expressed as cos(x).

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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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