Math Problem Statement

Find the equation of the line tangent to the graph of f(x) = 3 sin(x) - 2 cos(x) at x = -π.

Solution

The problem asks to find the equation of the line tangent to the graph of the function f(x)=3sin(x)2cos(x)f(x) = 3 \sin(x) - 2 \cos(x) at x=πx = -\pi.

Steps to solve:

  1. Find the derivative of the function f(x)f(x). This will give us the slope of the tangent line at any point xx.

    f(x)=ddx[3sin(x)2cos(x)]=3cos(x)+2sin(x)f'(x) = \frac{d}{dx} [3 \sin(x) - 2 \cos(x)] = 3 \cos(x) + 2 \sin(x)

  2. Evaluate the derivative at x=πx = -\pi to find the slope of the tangent line at this point.

    f(π)=3cos(π)+2sin(π)f'(-\pi) = 3 \cos(-\pi) + 2 \sin(-\pi)

    Since cos(π)=1\cos(-\pi) = -1 and sin(π)=0\sin(-\pi) = 0, we get:

    f(π)=3(1)+2(0)=3f'(-\pi) = 3(-1) + 2(0) = -3

    So, the slope of the tangent line is m=3m = -3.

  3. Find the value of the function at x=πx = -\pi to determine the point of tangency. This gives us the yy-coordinate of the point on the curve.

    f(π)=3sin(π)2cos(π)f(-\pi) = 3 \sin(-\pi) - 2 \cos(-\pi)

    Since sin(π)=0\sin(-\pi) = 0 and cos(π)=1\cos(-\pi) = -1, we get:

    f(π)=3(0)2(1)=2f(-\pi) = 3(0) - 2(-1) = 2

    The point of tangency is (π,2)(-\pi, 2).

  4. Write the equation of the tangent line using the point-slope form:

    yy1=m(xx1)y - y_1 = m(x - x_1)

    Substituting m=3m = -3, x1=πx_1 = -\pi, and y1=2y_1 = 2, we get:

    y2=3(x+π)y - 2 = -3(x + \pi)

    Simplifying:

    y=3(x+π)+2y = -3(x + \pi) + 2 y=3x3π+2y = -3x - 3\pi + 2

So, the equation of the tangent line is: y=3x3π+2y = -3x - 3\pi + 2

Would you like more details on any step? Here are some related questions you might explore:

  1. How is the derivative used to find the slope of a tangent line?
  2. What is the point-slope form of a line equation?
  3. Why do trigonometric functions have specific values at angles like π\pi and π-\pi?
  4. How would the tangent line differ if the slope at x=πx = -\pi were positive?
  5. How does the chain rule apply when differentiating trigonometric functions?

Tip: Remember, the derivative tells you how fast the function is changing at a given point, which is why it helps define the slope of the tangent line.

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Math Problem Analysis

Mathematical Concepts

Calculus
Trigonometric Functions
Derivatives
Tangent Line

Formulas

Derivative of sin(x) = cos(x)
Derivative of cos(x) = -sin(x)
Point-slope form: y - y1 = m(x - x1)

Theorems

Differentiation of trigonometric functions

Suitable Grade Level

Grades 11-12 (or Calculus I)