Math Problem Statement

Line segment AB is shown on the coordinate plane. Line CD is the perpendicular bisector of line AB. A perpendicular bisector is perpendicular to the given line segment and intersects the line segment at its midpoint. What is the equation of line CD?

Solution

Let's analyze the image and solve the problem step by step.

Problem Breakdown:

  1. Line segment ABAB is shown on the coordinate plane.
  2. We are tasked with finding the equation of line CDCD, which is the perpendicular bisector of ABAB.
  3. A perpendicular bisector of a line segment:
    • Is perpendicular to the line.
    • Intersects the line at its midpoint.

Step 1: Coordinates of points A and B

From the graph:

  • Point AA is at (4,6)(4, 6).
  • Point BB is at (12,2)(12, 2).

Step 2: Midpoint of line segment ABAB

The midpoint formula is: M=(x1+x22,y1+y22)M = \left( \frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2} \right) Using A(4,6)A(4, 6) and B(12,2)B(12, 2): M=(4+122,6+22)=(8,4)M = \left( \frac{4 + 12}{2}, \frac{6 + 2}{2} \right) = (8, 4)

Step 3: Slope of line segment ABAB

The slope formula is: m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1} Substitute the coordinates of A(4,6)A(4, 6) and B(12,2)B(12, 2): mAB=26124=48=12m_{AB} = \frac{2 - 6}{12 - 4} = \frac{-4}{8} = -\frac{1}{2}

Step 4: Slope of perpendicular bisector

The slope of the perpendicular bisector is the negative reciprocal of the slope of ABAB. So, if the slope of ABAB is 12-\frac{1}{2}, the slope of CDCD will be: mCD=2m_{CD} = 2

Step 5: Equation of line CDCD

The equation of a line in slope-intercept form is: yy1=m(xx1)y - y_1 = m(x - x_1) Using the midpoint M(8,4)M(8, 4) and the slope 22, we can plug into the point-slope form: y4=2(x8)y - 4 = 2(x - 8) Simplifying: y4=2x16y - 4 = 2x - 16 y=2x12y = 2x - 12

Final Answer:

The equation of line CDCD is: y=2x12y = 2x - 12

Would you like more details or explanations on any part?

Here are some related questions:

  1. How do you find the slope of a line between two points?
  2. What is the significance of the perpendicular bisector in geometry?
  3. How do you use the midpoint formula to find the center of a line segment?
  4. What are the characteristics of parallel and perpendicular lines?
  5. How can we check if two lines are perpendicular using their slopes?

Tip: The negative reciprocal rule is key when working with perpendicular lines—always remember to flip and change the sign of the slope.

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Math Problem Analysis

Mathematical Concepts

Geometry
Algebra
Coordinate Plane
Slopes

Formulas

Midpoint formula: M = ((x1 + x2) / 2, (y1 + y2) / 2)
Slope formula: m = (y2 - y1) / (x2 - x1)
Point-slope form of a line: y - y1 = m(x - x1)

Theorems

Perpendicular lines have slopes that are negative reciprocals

Suitable Grade Level

Grades 9-11