Areas of common shapes

To paint, wallpaper or panel a wall, students must know the total area of the wall so they can buy the appropriate amount of finish. When designing a new building, or seeking planning permission, it is often necessary to specify the total floor area of the building. In construction, calculating the area of a gable end of a building is important when determining the amount of bricks and mortar to order. Area is a measure of the size or extent of a plane surface. It is measured in square units such as mm², cm² and m². The chapter deals with finding areas of common shapes. There are five types of quadrilateral, these being rectangle, square, parallelogram, rhombus and trapezium. If the opposite corners of any quadrilateral are joined by a straight line, two triangles are produced. Since the sum of the angles of a triangle is 180°, the sum of the angles of a quadrilateral is 360°.