Math Problem Statement

In a trapezium ABCD, AB ‖ CD. If OA = x + 5, OB = x – 7, OC = x + 3 and OD = x – 2, then find x

Solution

To solve for xx in this trapezium problem, we will use the fact that in any trapezium where ABCDAB \parallel CD, if the diagonals are drawn and intersect at point OO, the following property holds:

OAOB=OCOD\frac{OA}{OB} = \frac{OC}{OD}

Given:

  • OA=x+5OA = x + 5
  • OB=x7OB = x - 7
  • OC=x+3OC = x + 3
  • OD=x2OD = x - 2

Using the property, we can set up the equation:

OAOB=OCOD\frac{OA}{OB} = \frac{OC}{OD}

Substituting the given values:

x+5x7=x+3x2\frac{x + 5}{x - 7} = \frac{x + 3}{x - 2}

Now, we will solve this equation step-by-step.

  1. Cross-multiply:

(x+5)(x2)=(x7)(x+3)(x + 5)(x - 2) = (x - 7)(x + 3)

  1. Expand both sides:

(x+5)(x2)=x22x+5x10=x2+3x10(x + 5)(x - 2) = x^2 - 2x + 5x - 10 = x^2 + 3x - 10 (x7)(x+3)=x2+3x7x21=x24x21(x - 7)(x + 3) = x^2 + 3x - 7x - 21 = x^2 - 4x - 21

  1. Set the expanded forms equal to each other:

x2+3x10=x24x21x^2 + 3x - 10 = x^2 - 4x - 21

  1. Simplify by subtracting x2x^2 from both sides:

3x10=4x213x - 10 = -4x - 21

  1. Add 4x4x to both sides:

7x10=217x - 10 = -21

  1. Add 10 to both sides:

7x=117x = -11

  1. Divide by 7:

x=117x = -\frac{11}{7}

Thus, the value of xx is 117-\frac{11}{7}.

Do you want more details, or do you have any questions?


Here are 5 related questions:

  1. What is the formula for the area of a trapezium?
  2. How do the properties of parallel sides in a trapezium affect its diagonals?
  3. Can the diagonals of a trapezium be equal? Under what conditions?
  4. What are the different types of trapeziums, and how do their properties differ?
  5. How do you derive the equation of a line parallel to another in geometry?

Tip: In a trapezium, the diagonals generally do not bisect each other, but they divide each other proportionally when the sides are parallel.

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Math Problem Analysis

Mathematical Concepts

Algebra
Proportionality
Geometry of Trapeziums

Formulas

(OA/OB) = (OC/OD)

Theorems

Diagonals of trapeziums with parallel sides divide each other proportionally

Suitable Grade Level

Grades 9-11