Math Problem Statement

If AB is a tangent to the curve y = ln(x/2) at point C(1, y) and intersects X-axis at point A and Y-axis at point B, find the length of AB.

Solution

We are given the following problem:

  • A tangent line AB\overline{AB} is drawn to the curve y=ln(x2)y = \ln\left(\frac{x}{2}\right) at the point C(1,y)C(1, y).
  • The line intersects the x-axis at point AA and the y-axis at point BB.
  • We are tasked with finding the length of the tangent line AB\overline{AB}.

Steps to solve:

  1. Find the derivative of the function y=ln(x2)y = \ln\left(\frac{x}{2}\right). dydx=1x\frac{dy}{dx} = \frac{1}{x} This gives us the slope of the tangent line at any point on the curve.

  2. Find the slope of the tangent line at point C(1,y)C(1, y): At C(1,y)C(1, y), the slope of the tangent line is: dydxx=1=11=1\frac{dy}{dx}\Big|_{x=1} = \frac{1}{1} = 1 So, the slope of the tangent line at point C(1,0)C(1, 0) is 1.

  3. Equation of the tangent line: The equation of the tangent line in point-slope form is: yy1=m(xx1)y - y_1 = m(x - x_1) Substituting m=1m = 1 and (x1,y1)=(1,ln(12))=(1,ln2)(x_1, y_1) = (1, \ln\left(\frac{1}{2}\right)) = (1, -\ln 2): y(ln2)=1(x1)y - (-\ln 2) = 1(x - 1) y+ln2=x1y + \ln 2 = x - 1 y=x1ln2y = x - 1 - \ln 2 This is the equation of the tangent line.

  4. Find the x-intercept (point A): To find the x-intercept, set y=0y = 0 and solve for xx: 0=x1ln20 = x - 1 - \ln 2 x=1+ln2x = 1 + \ln 2 So, point AA is (1+ln2,0)(1 + \ln 2, 0).

  5. Find the y-intercept (point B): To find the y-intercept, set x=0x = 0 and solve for yy: y=01ln2y = 0 - 1 - \ln 2 y=1ln2y = -1 - \ln 2 So, point BB is (0,1ln2)(0, -1 - \ln 2).

  6. Calculate the length of AB\overline{AB}: The length of the line segment AB\overline{AB} can be calculated using the distance formula: Length of AB=(x2x1)2+(y2y1)2\text{Length of } \overline{AB} = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2} Substituting the coordinates of points A(1+ln2,0)A(1 + \ln 2, 0) and B(0,1ln2)B(0, -1 - \ln 2): Length of AB=(0(1+ln2))2+((1ln2)0)2\text{Length of } \overline{AB} = \sqrt{(0 - (1 + \ln 2))^2 + ((-1 - \ln 2) - 0)^2} =(1+ln2)2+(1ln2)2= \sqrt{(1 + \ln 2)^2 + (-1 - \ln 2)^2} =(1+ln2)2+(1+ln2)2= \sqrt{(1 + \ln 2)^2 + (1 + \ln 2)^2} =2(1+ln2)2= \sqrt{2(1 + \ln 2)^2} =2(1+ln2)= \sqrt{2}(1 + \ln 2) Hence, the length of AB\overline{AB} is: 2(1+ln2)units\boxed{\sqrt{2}(1 + \ln 2) \, \text{units}}

Would you like further clarification on any step? Here are five related questions:

  1. How would the equation of the tangent line change if the point of tangency were different?
  2. Can we find the length of AB\overline{AB} using a different method?
  3. How do we interpret the natural logarithmic function geometrically on this curve?
  4. What happens to the slope of the tangent line as xx \to \infty?
  5. What role does the point C(1,y)C(1, y) play in determining the tangent's properties?

Tip: Always differentiate the function first when dealing with tangent lines to a curve!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Tangent Line to a Curve
Logarithmic Functions
Slope of Tangent
Distance Formula

Formulas

dy/dx = 1/x
Equation of a Line: y - y1 = m(x - x1)
Distance Formula: d = sqrt((x2 - x1)^2 + (y2 - y1)^2)

Theorems

Tangent to a Curve
Derivative of Logarithmic Function

Suitable Grade Level

Grades 11-12 (Pre-Calculus/Calculus)