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CHAPTER – 10 Mensuration Perimeter is the length of the boundary of the geometric shape.
In other words 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 in which all sides and angles are equal 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 than half a square is in a region. Count it as one square (c) If exactly half the square is counted, take its area as
Area of a rectangle = length × breadth Area of a square = side × side
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