# 6th Class Mathematics Mensuration Mensuration (Perimeter & Area, Review of Earlier Concepts)

Mensuration (Perimeter & Area, Review of Earlier Concepts)

Category : 6th Class

MENSURATION

(Perimeter and Area, Review of Earlier Concepts)

FUNDAMENTALS

•                         Area is the part of plane occupied by the closed figure.

(a) Perimeter of a square $=4\,\,\times$side.

Elementary question-1: Find perimeter of a square kabaddi field each of whose side is 20 metres Ans. Perimeter $4\times 20=80\,\,m$

(b) Perimeter of a rectangle $=2\times$ (length + breadth) units.

(c) Area of a square = (side $\times$ side).

(d) Area of a rectangle = length $\times$ breadth.

(e) Area of a parallelogram = base $\times$ height sq. units.

(f) Area of a triangle $=\frac{1}{2}$ (Area of the parallelogram generated from it)

$=\frac{1}{2}\times$base $\times$ height sq. units

•                      If the length of sides of a triangle are a, b, c and $s=\frac{a+b+c}{2}=$ half perimeter, then area is given as$\Delta =\sqrt{s\left( s-a \right)\left( s-b \right)\left( s-c \right)}$
•                      Circumference of a Circle: The perimeter of a circle is called its circumference.

Circumference $=2\pi r=\pi d,$ where $r=$radius and $d=$diameter.

Here $\pi \,\,(Pi)$ is a constant, equal to$3.14$     approximately.

•                       Area of a circle: Area of a circle with radius r units is equal to $\pi {{r}^{2}}sq$units.

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