MENSURATION | SPEED NOTES | CBSE | MATHEMATICS | CLASS 6

CHAPTER – 10 Mensuration Perimeter is the distance covered along theboundary forming aclosed figure whenyou go round the figure once. (a) Perimeter of arectangle = 2 × (length + breadth) (b) Perimeter of a square = 4 × length ofits side (c) Perimeter of anequilateral triangle =3 × length of a side (d) Perimeter of a regular pentagon has five equal sides = 5 × length of a sides Figures inwhich all sides and angles areequal are called regular closed figures. The amount of surface enclosed by a closed figure is called its area. To calculate the area of a figure using a squared paper, the following conventions are adopted : (a) Ignore portions ofthe area thatare less thanhalf a square. (b) If more thanhalf a square is in a region. Count it as onesquare (c) If exactly halfthe square iscounted, take itsarea as Area of a rectangle = length × breadth Area of a square = side × side (1/2)sq units.