Knowledge of quantities / calculating areas Knowledge of technical information, quantaties and communicating with others

Private and Confidential2 A Saint-Gobain company Area - Rectangles (1) Area is used in construction for costing work and estimating quantities. It is normally measured in squared metres. A square metre is the surface of a square measuring 1 metre by 1 metre, and is written as 1m 2. It is calculated by multiplying the two sides together. It is the space that counts the area, not the shape. 1m 2m 0.5m 4m 0.25m

Private and Confidential3 A Saint-Gobain company Area - Rectangles (2) All areas of squares and rectangles are worked out in the same way. You simply multiply the length by the height. 3m x 4m = 12m2 5m x 2m = 10m2 2.5m x 4m = 10m2 3.5m x 2m = 7m2

Private and Confidential4 A Saint-Gobain company Area - Rectangles (3) Take out area Step 1: Work out the total area = 4m x 3m = 12 m 2 Step 2: Work out the area of the opening (s) = 2m x 1m = 2m 2 Step 3: take the openings from the total area = 12m 2 – 2m 2 = 10m 2 The area of the wall is 10m 2 4m 3m 2m 1m 12m 2 2m 2 10m 2

Private and Confidential5 A Saint-Gobain company Formulae – RECTANGLE H L Area = Length (L) x Height (H) = mm 2 or m 2

Private and Confidential6 A Saint-Gobain company Area Triangles (4) The area of a triangle is always half the area of a square with the same base and height Area of a triangle = Base x Height / 2 HEIGHT BASE

Private and Confidential7 A Saint-Gobain company Formulae – TRIANGLE H B Area = ½ Base (B) x Height (H) = mm2 or m2

Private and Confidential8 A Saint-Gobain company Area of a gable end Step 1: Divide up the wall Step 2: Work out the area of each section: 3m x 4m = 12m 2 4m x 3m / 2m = 6m 2 Step 3: Add the two areas together 12m 2 + 6m 2 = 18m 2 The area of this gable is 18m 2 12m 2 4m 3m 4m 3m 6m 2 4m 3m 18m 2

Private and Confidential9 A Saint-Gobain company Area of Circles (1) The area of a circle is calculated using  (pi) = 3.14 The formula to find the area of any circle Area =  x radius x radius The radius (r) is the length from the centre to the edge The diameter (d) is the length from edge to edge, through the centre r d

Private and Confidential10 A Saint-Gobain company Area of Circles (2) 4m Circle Circle 3m Half Circle Half Circle 2m Quarter Circle Quarter Circle The area of this circle is =  x rad x rad = 3.14 x 4 x 4 = m2 The area of this half circle is = ( x rad x rad) / 2 = (3.14 x 3 x 3) / 2 = m2 The area of this quarter circle is = ( x rad x rad) / 4 = (3.14 x 2 x 2) / 4 = 3.14 m2

Private and Confidential11 A Saint-Gobain company Exercise (1) 4m 6m 2.5m 3.2m 14m 16m 3m 7.4m Area = m

Private and Confidential12 A Saint-Gobain company Formulae – CIRCLE Radius (r): Length from centre to outside edge (mm or m) Diameter (d): Length from edge to edge through centre (mm or m) Circumference (c): Perimeter or edge of circle = 2  r Area =  x r x r =  r 2 (mm 2 or m 2 ) r d c