Problem: Find the area of trapezium ABCD, given that AB is parallel to DC, AB = 29 cm, DC = 20 cm, AD = 15 cm, and BC = 12 cm.

Solution:
To find the area of the trapezium, we can use the formula:

Area = (1/2) * (sum of the lengths of the parallel sides) * (distance between the parallel sides)

In this case, the parallel sides are AB and DC, and the distance between them is AD. Therefore, the area of trapezium ABCD can be calculated as:

Area = (1/2) * (AB + DC) * AD

Now, let's substitute the given values into the formula:

Area = (1/2) * (29 + 20) * 15

Simplifying the expression:

Area = (1/2) * 49 * 15
Area = 24.5 * 15
Area = 367.5 square cm

Therefore, the area of trapezium ABCD is 367.5 square cm.

Points to Remember - Mensuration:
Mensuration is the branch of mathematics that deals with the measurement of geometric figures and their parameters such as length, area, volume, etc. Here are some important points to remember about mensuration:

1. Length: Length is a one-dimensional measurement that determines the distance between two points. It is measured using units such as centimeters (cm), meters (m), feet (ft), inches (in), etc.

2. Area: Area is a two-dimensional measurement that determines the amount of space occupied by a flat surface or shape. It is measured in square units such as square centimeters (cm²), square meters (m²), square feet (ft²), square inches (in²), etc.

3. Volume: Volume is a three-dimensional measurement that determines the amount of space occupied by a solid object. It is measured in cubic units such as cubic centimeters (cm³), cubic meters (m³), cubic feet (ft³), cubic inches (in³), etc.

4. Perimeter: Perimeter is the total distance around the boundary of a two-dimensional figure. It is measured in the same units as length.

5. Formulas: Mensuration involves various formulas to calculate the length, area, and volume of different geometric figures such as squares, rectangles, triangles, circles, cylinders, cones, etc. It is important to memorize these formulas and understand their applications.

6. Real-life Applications: Mensuration concepts are widely used in various real-life situations such as construction, architecture, engineering, land surveying, etc. They help in determining the dimensions, quantities, and costs related to different geometric figures.

By understanding and applying the principles of mensuration, we can solve a wide range of mathematical problems and make accurate measurements in practical scenarios.