ABSTRACT
A polygon is a closed plane figure bounded by straight lines. A polygon, which has:
(i) 3 sides is called a triangle (ii) 4 sides is called a quadrilateral
(iii) 5 sides is called a pentagon (iv) 6 sides is called a hexagon (v) 7 sides is called a heptagon (vi) 8 sides is called an octagon
(a) The girder may be divided into three separate rectangles as shown. Area of rectangle A 50 5 250 mm 2 Area of rectangle B (75 8 5) 6 62 6 372 mm 2 Area of rectangle C 70 8 560 mm 2 Total area of girder 250 372 560 1182 mm2 or 11.82 cm2
(b) Area of path area of large rectangle area of small rectangle (25 20) (21 16) 500 336
164 m2
Application: Find (a) the cross-sectional area of the girder shown in Figure 4.2(a) , and (b) the area of the path shown in Figure 4.2(b)
Application: Figure 4.3 shows the gable end of a building. Determine the area of brickwork in the gable end
The shape is that of a rectangle and a triangle.
