Math Problem Statement

  1. The point P = (1/4,1/ 2) lies on the curve y = cos(πx) where x is in radians, as shown below. y P −2 −1 0 1 2 x (a) If Q = (x, cos(πx)) then use your calculator to find the slope of the secant line P Q, rounded to four digits after the decimal point, for the following values of x: (i) 0.24, (ii) 0.249, (iii) 0.2499, (iv) 0.26, (v) 0.251, (vi) 0.2501.

Solution

To find the slope of the secant line PQPQ for each given value of xx, we will use the formula for the slope between two points, P=(14,12)P = \left(\frac{1}{4}, \frac{1}{2}\right) and Q=(x,cos(πx))Q = (x, \cos(\pi x)).

The slope formula between the two points is:

slope=y2y1x2x1=cos(πx)12x14\text{slope} = \frac{y_2 - y_1}{x_2 - x_1} = \frac{\cos(\pi x) - \frac{1}{2}}{x - \frac{1}{4}}

We will calculate this slope for each value of xx:

  1. x=0.24x = 0.24
  2. x=0.249x = 0.249
  3. x=0.2499x = 0.2499
  4. x=0.26x = 0.26
  5. x=0.251x = 0.251
  6. x=0.2501x = 0.2501

Let's calculate each slope rounded to four decimal places.Here are the slopes of the secant line PQPQ for each given value of xx, rounded to four decimal places:

  1. x=0.24x = 0.24: 22.8969-22.8969
  2. x=0.249x = 0.249: 209.3247-209.3247
  3. x=0.2499x = 0.2499: 2073.2889-2073.2889
  4. x=0.26x = 0.26: 18.454718.4547
  5. x=0.251x = 0.251: 204.8819204.8819
  6. x=0.2501x = 0.2501: 2068.84602068.8460

These values indicate how the slope of the secant line changes as xx approaches 14\frac{1}{4} (or 0.250.25).

Would you like to see more details or have any questions?

Related Questions:

  1. What is the significance of the slope values when xx is close to 0.25?
  2. How do you interpret the change in the slope of the secant line as xx approaches 0.25?
  3. Can we find the derivative of cos(πx)\cos(\pi x) at x=0.25x = 0.25 using limits?
  4. What happens to the slope of the secant line if xx moves further away from 0.25?
  5. How can this method be used to estimate the tangent line's slope at a point?

Tip: For small increments in xx, the secant line slope approximates the derivative at a point!

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Calculus
Slopes of secant lines
Derivatives

Formulas

Slope formula: (y2 - y1) / (x2 - x1)
y = cos(πx)

Theorems

Secant line slope as a difference quotient
Limit definition of a derivative

Suitable Grade Level

Grades 11-12 or Early College Calculus