Math Problem Statement

The formula A = 1/2 (a + b)h is used to find the area, A, of a trapezium where a and b are the lengths of the parallel sides and h is the distance between the parallel sides. The trapezium shown has an area of 27 cm². Work out the value of x.

Solution

We are given the formula for the area of a trapezium, A=12(a+b)hA = \frac{1}{2}(a + b)h, where:

  • aa and bb are the lengths of the parallel sides,
  • hh is the height (distance between the parallel sides),
  • AA is the area.

In the diagram:

  • a=4cma = 4 \, \text{cm},
  • b=5cmb = 5 \, \text{cm},
  • A=27cm2A = 27 \, \text{cm}^2,
  • h=xh = x (which we need to find).

Using the area formula, substitute the given values:

27=12(4+5)x27 = \frac{1}{2}(4 + 5) \cdot x

First, simplify the equation:

27=12(9)x27 = \frac{1}{2}(9) \cdot x

27=92x27 = \frac{9}{2} \cdot x

Multiply both sides by 2 to eliminate the fraction:

54=9x54 = 9x

Now, solve for xx:

x=549=6x = \frac{54}{9} = 6

So, the value of xx is 6 cm.

Would you like further clarification or a breakdown of any part of the solution?

Here are 5 related questions for practice:

  1. What is the area of a trapezium if the lengths of the parallel sides are 8 cm and 10 cm, and the height is 7 cm?
  2. If the area of a trapezium is 40 cm², and the lengths of the parallel sides are 6 cm and 4 cm, what is the height?
  3. How does the area of a trapezium change if the height is doubled while keeping the parallel sides constant?
  4. If a trapezium has an area of 36 cm², with one parallel side 5 cm and the height 4 cm, what is the length of the other parallel side?
  5. What is the relationship between the height and area of a trapezium for fixed lengths of the parallel sides?

Tip: Always ensure the units are consistent (e.g., all in cm or m) when using area formulas.

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Math Problem Analysis

Mathematical Concepts

Geometry
Area of a trapezium
Algebra

Formulas

A = 1/2 (a + b)h

Theorems

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Suitable Grade Level

Grades 7-9