Math Problem Statement

Point C is the midpoint of line segment AB. The ratio of the length of DC to the length of CE is 2 : 3. What are the coordinates of point D?

Solution

To solve this problem, let's analyze the given information and use the section formula.

Given:

  1. CC is the midpoint of line segment ABAB.
  2. The coordinates of AA are (12,3)(12, 3), and the coordinates of BB are (20,13)(20, 13).
  3. The coordinates of EE are (28,2)(28, 2).
  4. The ratio of the lengths DC:CE=2:3DC : CE = 2 : 3.
  5. We need to find the coordinates of point DD.

Steps to Solve:

  1. Find the Coordinates of CC: Since CC is the midpoint of ABAB, the coordinates of CC can be calculated as: C=(xA+xB2,yA+yB2)C = \left( \frac{x_A + x_B}{2}, \frac{y_A + y_B}{2} \right) Substituting the coordinates of AA and BB: C=(12+202,3+132)=(322,162)=(16,8)C = \left( \frac{12 + 20}{2}, \frac{3 + 13}{2} \right) = \left( \frac{32}{2}, \frac{16}{2} \right) = (16, 8)

  2. Use the Section Formula to Find DD: Since DD divides CECE in the ratio 2:32 : 3, we can use the section formula, which states: D=(mx2+nx1m+n,my2+ny1m+n)D = \left( \frac{m \cdot x_2 + n \cdot x_1}{m + n}, \frac{m \cdot y_2 + n \cdot y_1}{m + n} \right) where C=(x1,y1)C = (x_1, y_1) and E=(x2,y2)E = (x_2, y_2), and the ratio m:n=2:3m : n = 2 : 3.

    Substituting the values: D=(228+3162+3,22+382+3)D = \left( \frac{2 \cdot 28 + 3 \cdot 16}{2 + 3}, \frac{2 \cdot 2 + 3 \cdot 8}{2 + 3} \right) Calculating each coordinate: xD=56+485=1045=20.8x_D = \frac{56 + 48}{5} = \frac{104}{5} = 20.8 yD=4+245=285=5.6y_D = \frac{4 + 24}{5} = \frac{28}{5} = 5.6

Conclusion:

The coordinates of point DD are (20.8,5.6)(20.8, 5.6).

Would you like more details or have any questions about this solution?


Here are 5 related questions to expand understanding:

  1. How would the solution change if the ratio DC:CEDC : CE were different?
  2. What if CC was not the midpoint of ABAB; how would that affect the coordinates of CC?
  3. Can you determine the length of line segments DCDC and CECE with these coordinates?
  4. What if point DD were closer to CC than EE; how would that affect the coordinates?
  5. How could this problem be solved if only the graphical representation were given?

Tip: The section formula is a useful tool for dividing a line segment into any given ratio, and it can be applied in various geometry problems involving coordinates.

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Math Problem Analysis

Mathematical Concepts

Coordinate Geometry
Ratios
Midpoint Formula
Section Formula

Formulas

Midpoint formula
Section formula

Theorems

Section formula theorem

Suitable Grade Level

Grade 10