The amount of surface of an object is called its area. Area is represented in units squared, for example a sheet of paper is 93.5 inches².
You can visualize how area is measured by dividing what you are measuring into small squares of the units you are measuring into. For example, a standard piece of paper is 8½ inches wide and 11 inches tall. If you put squares that are 1 inch tall by 1 inch wide on the paper and count the number of squares needed to cover the paper you are measuring the area. In the image below there are 88 whole squares and 11 half squares. The total number of squares is 93.5 squares.
Area of a Square
Area = side²
To find a square’s area, just square one of its sides.
Area of a Rectangle
Area = length x width
To find a rectangles area, simply multiply its length times its width.
A = 7 x 4
A = 28 yards²
Area of a Triangle
Area = ½ x base x height
To find a triangle’s area, you need to know the length of its height and its base. Multiply the base times the height and then multiply that by ½ (or 0.5).
In the video below I calculate the area of a rectangle and square together. Notice that it is much easier to calculate the area of the triangle as one triangle rather than using the Pythagorean theorem and finding the area of the two triangles, as it seems they are suggesting you do by how they label the measurements.
Area of a Circle
Area = π x radius²