Question

What is perimeter and area: triangle, rectangle, square, polygon and circle?

Answer 1

To find the Perimeter and Area of any shape, there are some fixed formulas.

Following are some of them-


Perimeter of triangle = the sum of all sides i.e.
$p = a + b + c$
Area of Triangle = half of the product of its base and its height i.e.
$area = \frac{1}{2} \times b \times h$
Area of equilateral triangle = √3/4 × the square of its side i.e.
$area = \frac{ \sqrt{3} }{4} \times {a}^{2}$

Perimeter of Rectangle = 2 times the sum of its length and its breadth i.e.
$p = 2(l + b)$
Area of rectangle = the product of its length and its breadth i.e.
$a = l \times b$

Perimeter of square = 4 times it's side i.e.
$p = a \times 4$
Area of square = square of its side i.e.
$area = {a}^{2}$

Perimeter of a circle is called circumference
Circumference of a circle = 2 × pi × radius i.e.
$c = 2\pi r$
Area if circle = pi × the square of its radius i.e.
$a = \pi {r}^{2}$

Polygons can have many sides.
Perimeter of any polygon = the sum of all sides i.e.
$p = a + b + c.....$
Area of any polygon = half of the product of its Perimeter and its apothem (Apothem is the line which joins the middle of any polygon to the midpoint of any of its sides)
$area = \frac{1}{2} \times perimeter \times apotem$
$area = \frac{1}{2} \times p \times a$


So those are the formulas for finding the area and Perimeter of some shapes.
Hope it'll help. :-D

Answer 2

Triangle :

Perimeter = a+b+c

Area = √[ s (a-s) (b-s) (c-s) ]

Rectangle :

Perimeter = 2×(l+b)

Area = l × b

Square :

Perimeter = 4s

Area = s²

Polygon :

Perimeter = a+b+c+....

Area = 1/2 × perimeter × apothem

Circle :

Perimeter = 2πr

Area = πr²

HOPE IT HELPS

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