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All the Triangle , Circle , Square, and Rectangle are plan figure . The total length of the boundary lines of plan figure is called its perimeter.Perimeter of Triangles :
The sum of the length of its three sides is known as a perimeter of triangles . Therefore,
\(\therefore\) Perimeter of \(\triangle DEF\) =DE + EF+ FD = a+b+c
The half of its perimeter is known as semi -perimeter of triangle . It is denoted by the letter 's'.
\(\therefore\) Semi -perimeter of \(\triangle\)DEF= \(\frac{a+b+c}{2}\)
The opposite sides of rectangle are always equal . So , the lengths = EF=GH=l
the breadths =FH=EG=b
The perimeter of the rectangles EFGH =EF+FG+GH+HG
=l+b+l+b=2l+2b
=2(l+b)
\(\therefore\)Perimeter of rectangle = 2(l+b)
In the case of Square , its perimeter =2(l+l)
=2x2l=4l
At first draw three circles with radii 2cm , 3cm, and 4cm, and place the pieces of strings along the circumference of each separately .
Then start measuring the length of each string separately with the help of scale . Then, find the ratios of the length of the circumference of each circle to its diameter . Now , you all will find the ratio \(\frac{circumference}{diameter}\) is almost the same for every circle. The constant ratio is represented by Greek letter 'π' (pie). So , the circumference of circle iscand its diameter bed,
Now , \(\frac{circumfernce }{diameter})=π
or, \(\frac{c}{d})=π
or, c=πd
Diameter of circle (d) =2xradius (r).
So, circumference or the perimeter of circle (c) =2πr
The perimeter of circle =πd or2πr
Solution:
Here,
the length of the field (l) = 25 m
the perimeter of the field = 86 m
Now,
the perimeter of the rectangular field = 86 m
or, 2(l + b) = 86 m
or, 25 + b = \(\frac{86}{2}\) m
or, 25 + b = 43 m
or, b = (43 - 25) m
or, b = 18 m
∴ the required breadth of the field is 18 m
Solution:
Here,
the radius of the circular ground (r) = 35m
its perimeter = 2πr
= 2 × \(\frac{22}{7}\) × 35 m
= 2 × 22 × 5
= 220 m
∴ The required length of wire = 4 × 220m
= 880 m
Again,
the required cost of fencing = 880 × Rs 10
= Rs 8800
What is the formula of perimeter of rectangle?
What is the formula of perimeter of a circle?
What is the formula of a semi-perimeter of a triangle?
If the perimeter of a rectangular field of length 25m is 86m, what will be its breadth.
If the perimeter of a circular ground is 352m, what will be its radius?
If the circumference of a circular field is 132m then what will be its diameter.
In the equilateral triangle whose one of the side is 4.5 cm them what will be its perimeter?
Find the semi-perimeter of a triangular park whose lengths are 15m, 20.5m and 17.5m.
The Semi-perimeter of a triangle is denoted by ______.
The value of "π" is ______ .
ASK ANY QUESTION ON Perimeter
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