Math Problem Statement

ABCD is a parallelogram. What are the coordinates of point D? Given points: A(-11, 23), B(-13, 29), and C(5, 22).

Solution

We are given that ABCD is a parallelogram, and we need to find the coordinates of point D. We have the following information:

  • A(11,23)A(-11, 23)
  • B(13,29)B(-13, 29)
  • C(5,22)C(5, 22)

To find the coordinates of point D, we can use the property of parallelograms: the diagonals bisect each other. This means the midpoint of diagonal AC is the same as the midpoint of diagonal BD.

Let's find the midpoint of diagonal AC:

Midpoint of AC=(11+52,23+222)=(62,452)=(3,22.5)\text{Midpoint of AC} = \left( \frac{-11 + 5}{2}, \frac{23 + 22}{2} \right) = \left( \frac{-6}{2}, \frac{45}{2} \right) = (-3, 22.5)

Now, let the coordinates of point D be (x,y)(x, y). Using the fact that the midpoint of BD must also be (3,22.5)(-3, 22.5), we can set up the midpoint formula for BD:

(13+x2,29+y2)=(3,22.5)\left( \frac{-13 + x}{2}, \frac{29 + y}{2} \right) = (-3, 22.5)

Now, solve for xx and yy:

  1. 13+x2=3\frac{-13 + x}{2} = -3

    Multiplying both sides by 2:

    13+x=6x=7-13 + x = -6 \quad \Rightarrow \quad x = 7

  2. 29+y2=22.5\frac{29 + y}{2} = 22.5

    Multiplying both sides by 2:

    29+y=45y=1629 + y = 45 \quad \Rightarrow \quad y = 16

Thus, the coordinates of point D are (7,16)(7, 16).

Would you like further details, or do you have any other questions?

Here are 5 related questions to deepen your understanding:

  1. How can you confirm that opposite sides of a parallelogram are parallel using vectors?
  2. How can the area of parallelogram ABCD be calculated using the vertices' coordinates?
  3. Can you apply this method to find a missing vertex of a trapezoid or other quadrilaterals?
  4. How would you find the equation of the line passing through two points, like A and B?
  5. What are some other properties of parallelograms that can help solve geometric problems?

Tip: In geometry, the midpoint formula is an essential tool for solving problems involving bisected diagonals, line segments, or centroids.

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Math Problem Analysis

Mathematical Concepts

Geometry
Coordinate Geometry
Midpoint Formula
Properties of Parallelograms

Formulas

Midpoint formula: Midpoint = ((x1 + x2)/2, (y1 + y2)/2)
Properties of parallelogram: Diagonals bisect each other

Theorems

Diagonals of a parallelogram bisect each other

Suitable Grade Level

Grades 8-10