Math Problem Statement

The midpoint of line segment AB is M(-1, 2). If the coordinates of A are (4, 5), what are the coordinates of B?

Solution

The problem provided is asking for the coordinates of point BB given that the midpoint MM of segment AB\overline{AB} is M(1,2)M(-1, 2) and the coordinates of point AA are A(4,5)A(4, 5).

To solve this:

We know the formula for the midpoint MM of a line segment AB\overline{AB} is:

M=(x1+x22,y1+y22)M = \left( \frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2} \right)

Where:

  • (x1,y1)(x_1, y_1) are the coordinates of point AA,
  • (x2,y2)(x_2, y_2) are the coordinates of point BB,
  • M(xm,ym)M(x_m, y_m) is the midpoint.

Given:

  • M=(1,2)M = (-1, 2),
  • A=(4,5)A = (4, 5).

Let the coordinates of BB be B(x2,y2)B(x_2, y_2). Using the midpoint formula, we can set up the following equations:

1=4+x22(for the x-coordinates)-1 = \frac{4 + x_2}{2} \quad \text{(for the x-coordinates)} 2=5+y22(for the y-coordinates)2 = \frac{5 + y_2}{2} \quad \text{(for the y-coordinates)}

Solving for x2x_2 and y2y_2:

  1. For the x-coordinate: 1=4+x22-1 = \frac{4 + x_2}{2} Multiply both sides by 2: 2=4+x2-2 = 4 + x_2 Subtract 4 from both sides: x2=6x_2 = -6

  2. For the y-coordinate: 2=5+y222 = \frac{5 + y_2}{2} Multiply both sides by 2: 4=5+y24 = 5 + y_2 Subtract 5 from both sides: y2=1y_2 = -1

Final Answer:

The coordinates of point BB are (6,1)(-6, -1).

Would you like more details or have any questions?

Here are 5 related questions to expand on this concept:

  1. How do you calculate the distance between two points?
  2. What is the formula for finding the slope of a line given two points?
  3. How do you determine if two segments are perpendicular or parallel based on their slopes?
  4. Can you find the equation of a line given its midpoint and one point on the line?
  5. How do you find the area of a triangle given its three vertices?

Tip: When solving midpoint problems, always double-check your algebra by verifying that the computed midpoint matches the given value.

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Math Problem Analysis

Mathematical Concepts

Algebra
Coordinate Geometry
Midpoints

Formulas

Midpoint Formula: M = ((x1 + x2) / 2, (y1 + y2) / 2)

Theorems

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Suitable Grade Level

Grades 8-10