Math Problem Statement

Find the equation of the tangent line to y = 6 sin x + 7 sec x at x = π.

Solution

To find the equation of the tangent line to the curve y=6sinx+7secxy = 6 \sin x + 7 \sec x at x=πx = \pi, we will proceed as follows:

1. Find the derivative of the function:

The derivative dydx\frac{dy}{dx} will give us the slope of the tangent line.

  • Derivative of 6sinx6 \sin x is 6cosx6 \cos x.
  • Derivative of 7secx7 \sec x is 7secxtanx7 \sec x \tan x.

Thus, the derivative is:

dydx=6cosx+7secxtanx\frac{dy}{dx} = 6 \cos x + 7 \sec x \tan x

2. Evaluate the derivative at x=πx = \pi:

Now, substitute x=πx = \pi into the derivative to find the slope at that point.

  • cos(π)=1\cos(\pi) = -1
  • sec(π)=1\sec(\pi) = -1 (since sec(x)=1cos(x)\sec(x) = \frac{1}{\cos(x)})
  • tan(π)=0\tan(\pi) = 0

Therefore:

dydxx=π=6(1)+7(1)(0)=6\frac{dy}{dx}\bigg|_{x = \pi} = 6(-1) + 7(-1)(0) = -6

So, the slope of the tangent line at x=πx = \pi is m=6m = -6.

3. Find the point on the curve at x=πx = \pi:

To find the equation of the tangent line, we need the point on the curve at x=πx = \pi. Substitute x=πx = \pi into the original function:

y=6sin(π)+7sec(π)y = 6 \sin(\pi) + 7 \sec(\pi)

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

y=6(0)+7(1)=7y = 6(0) + 7(-1) = -7

Thus, the point is (π,7)(\pi, -7).

4. Equation of the tangent line:

The equation of the tangent line is given by the point-slope form:

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

Substitute m=6m = -6, x1=πx_1 = \pi, and y1=7y_1 = -7:

y+7=6(xπ)y + 7 = -6(x - \pi)

Simplify:

y=6x+6π7y = -6x + 6\pi - 7

Thus, the equation of the tangent line is:

y=6x+6π7y = -6x + 6\pi - 7

Would you like further details on this solution, or do you have any questions? Here are five related questions you might find interesting:

  1. How do you find the derivative of trigonometric functions like sec(x)\sec(x)?
  2. What is the general form of a tangent line equation?
  3. How does the derivative represent the slope of a function at a given point?
  4. Can you apply this method to other points on the curve?
  5. How do you handle more complex trigonometric derivatives?

Tip: Always evaluate trigonometric functions like sine, cosine, and secant carefully at special angles like π\pi, π2\frac{\pi}{2}, etc., as their values can simplify the calculations significantly.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Trigonometry
Derivatives
Tangent Line

Formulas

Derivative of sin(x) = cos(x)
Derivative of sec(x) = sec(x) * tan(x)
Tangent Line Formula: y - y1 = m(x - x1)

Theorems

Point-slope form of a line
Derivative rules for trigonometric functions

Suitable Grade Level

Grades 11-12