Math Problem Statement

Find the equation of the tangent line to the graph of F(x) at x = 1, where F(x) is defined as the integral from sqrt(x) to x of tan(t) dt.

Solution

We are tasked with finding the equation of the tangent line to the graph of the given function F(x)F(x) at x=1x = 1. The function is defined as:

F(x)=xxtan(t)dtF(x) = \int_{\sqrt{x}}^{x} \tan(t) \, dt

Solution Steps:

  1. Differentiate F(x)F(x) using the Fundamental Theorem of Calculus: The function F(x)F(x) involves both the upper and lower limits as functions of xx. To differentiate, we apply the Leibniz rule:

    F(x)=tan(x)ddx(x)tan(x)ddx(x)F'(x) = \tan(x) \cdot \frac{d}{dx}(x) - \tan(\sqrt{x}) \cdot \frac{d}{dx}(\sqrt{x})

    This simplifies to:

    F(x)=tan(x)tan(x)12xF'(x) = \tan(x) - \tan(\sqrt{x}) \cdot \frac{1}{2\sqrt{x}}

  2. Evaluate F(x)F'(x) at x=1x = 1: Substitute x=1x = 1 into F(x)F'(x):

    F(1)=tan(1)tan(1)121F'(1) = \tan(1) - \tan(\sqrt{1}) \cdot \frac{1}{2\sqrt{1}}

    Since 1=1\sqrt{1} = 1, this becomes:

    F(1)=tan(1)tan(1)12F'(1) = \tan(1) - \tan(1) \cdot \frac{1}{2}

    Simplify further:

    F(1)=tan(1)(112)=tan(1)2F'(1) = \tan(1) \left(1 - \frac{1}{2}\right) = \frac{\tan(1)}{2}

  3. Find F(1)F(1): To calculate F(1)F(1), evaluate the definite integral:

    F(1)=11tan(t)dtF(1) = \int_{\sqrt{1}}^{1} \tan(t) \, dt

    Since the lower and upper limits are the same (1=1\sqrt{1} = 1), the value of the integral is:

    F(1)=0F(1) = 0

  4. Equation of the tangent line: The equation of the tangent line at x=1x = 1 is:

    yF(1)=F(1)(x1)y - F(1) = F'(1)(x - 1)

    Substitute F(1)=0F(1) = 0 and F(1)=tan(1)2F'(1) = \frac{\tan(1)}{2}:

    y=tan(1)2(x1)y = \frac{\tan(1)}{2}(x - 1)

Final Answer:

The equation of the tangent line is:

y=tan(1)2(x1)y = \frac{\tan(1)}{2}(x - 1)

Would you like me to elaborate further or compute approximations for tan(1)\tan(1)?

Here are some related questions for further exploration:

  1. How do we evaluate the integral of trigonometric functions for different limits?
  2. What is the geometric interpretation of F(x)F(x) as a function involving definite integrals?
  3. How does the Leibniz rule apply when the limits of integration depend on xx?
  4. What is the significance of the slope of the tangent line in the context of F(x)F(x)?
  5. Can we derive higher-order derivatives of F(x)F(x) using similar techniques?

Tip: Always verify your differentiation steps when working with integral bounds that are functions of xx.

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Math Problem Analysis

Mathematical Concepts

Calculus
Definite Integrals
Differentiation
Tangent Lines

Formulas

F(x) = \int_{\sqrt{x}}^{x} \tan(t) \, dt
Leibniz Rule for differentiating integrals with variable limits
Equation of a tangent line: y - F(a) = F'(a)(x - a)

Theorems

Fundamental Theorem of Calculus
Leibniz Rule for differentiation of integrals

Suitable Grade Level

Grades 11-12