Math Problem Statement

Find the equations of the tangent line and normal lines to the graph of the function f(x) = 3 \sin x at x = \pi/2.

Solution

We are tasked with finding the equations of the tangent line and the normal line to the function f(x)=3sin(x)f(x) = 3 \sin(x) at x=π2x = \frac{\pi}{2}.

Step 1: Find the value of f(x)f(x) at x=π2x = \frac{\pi}{2}

We first evaluate the function f(x)f(x) at x=π2x = \frac{\pi}{2}: f(π2)=3sin(π2)=3×1=3f\left(\frac{\pi}{2}\right) = 3 \sin\left(\frac{\pi}{2}\right) = 3 \times 1 = 3 So, the point on the graph is (π2,3)\left( \frac{\pi}{2}, 3 \right).

Step 2: Find the derivative of f(x)f(x) (the slope of the tangent line)

To get the slope of the tangent line, we differentiate f(x)=3sin(x)f(x) = 3 \sin(x): f(x)=3cos(x)f'(x) = 3 \cos(x) Now, substitute x=π2x = \frac{\pi}{2} into the derivative: f(π2)=3cos(π2)=3×0=0f'\left(\frac{\pi}{2}\right) = 3 \cos\left(\frac{\pi}{2}\right) = 3 \times 0 = 0 The slope of the tangent line at x=π2x = \frac{\pi}{2} is 0.

Step 3: Equation of the tangent line

The general form of the equation of a line is: yy1=m(xx1)y - y_1 = m(x - x_1) Here, m=0m = 0, x1=π2x_1 = \frac{\pi}{2}, and y1=3y_1 = 3. Substituting these values: y3=0(xπ2)y - 3 = 0(x - \frac{\pi}{2}) y=3y = 3 Thus, the equation of the tangent line is: y=3\boxed{y = 3}

Step 4: Slope of the normal line

The slope of the normal line is the negative reciprocal of the slope of the tangent line. Since the slope of the tangent line is 0, the slope of the normal line will be undefined, meaning the normal line is a vertical line.

Step 5: Equation of the normal line

Since the normal line is vertical and passes through x=π2x = \frac{\pi}{2}, the equation of the normal line is: x=π2\boxed{x = \frac{\pi}{2}}

Final Answer:

  • The equation of the tangent line is y=3y = 3.
  • The equation of the normal line is x=π2x = \frac{\pi}{2}.

Would you like further details or have any questions?

Here are 5 related questions for practice:

  1. Find the tangent and normal lines to f(x)=sin(x)f(x) = \sin(x) at x=π3x = \frac{\pi}{3}.
  2. Find the equation of the tangent line to f(x)=cos(x)f(x) = \cos(x) at x=π4x = \frac{\pi}{4}.
  3. Determine the slope of the tangent line to f(x)=2sin(x)+x2f(x) = 2\sin(x) + x^2 at x=0x = 0.
  4. What is the equation of the tangent line to f(x)=exsin(x)f(x) = e^x \sin(x) at x=0x = 0?
  5. Find the point where the tangent line to f(x)=3x2sin(x)f(x) = 3x - 2 \sin(x) is horizontal.

Tip: The slope of a normal line is always the negative reciprocal of the slope of the tangent line at the same point.

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Math Problem Analysis

Mathematical Concepts

Calculus
Trigonometry
Derivatives
Tangent Line
Normal Line

Formulas

Derivative of sin(x): d/dx[sin(x)] = cos(x)
Point-slope form of a line: y - y1 = m(x - x1)

Theorems

Derivative of Trigonometric Functions
Tangent-Normal Line Relationship

Suitable Grade Level

Grades 11-12, Calculus I