1. Perimeter of Rectangle and Regular Shapes

Chapter 10

Mensuration

Perimeter of Rectangle and Regular Shapes

Introduction to perimeter,

Any shape that lies on a flat exterior and has only two extent i.e. length and breadth are called 2- D (two- dimensional) shape.
Polygons are closed numbers which are bounded by a chain of line parts, for illustration, triangles, squares, and squares. Perimeter (peri around; meter measure) of a polygon is the distance or direct measure of these bounded line parts. In other words, it is the length of its boundaries. Its unit is centimetre (cm) or meter (m).

 Perimeter of a rectangle,

Rectangle is a four- sided polygon having two range i.e. length and breadth.
Perimeter of a cube = sum of four sides

= AB + BC+ CD+ AD

= length + breadth +length+ breadth = 2 length +2 breadth

Perimeter of a rectangle = 2 × (length+ breadth)

Perimeter of a square

Square is also a polygon where all its sides are the same.
The perimeter of a square = sum of all four sides
= a + a + a+ a

= 4a
The perimeter of a square = 4 × side
The sum of the lengths of the sides is the perimeter of any polygon. In the case of a triangle,
Perimeter = Sum of the three sides
Always include units in the final answer. If the sides of the triangle are measured in centimetres, then the final answer should also be in centimetres.

Perimeter of a triangle

The formula for the perimeter of a closed shape figure is usually equal to the length of the outer line of the figure. Therefore, in the case of a triangle, the perimeter will be the sum of all the three sides. If a triangle has three sides a, b and c, then,
Perimeter, P = a + b +c

Perimeter of an Isosceles, Equilateral and Scalene Triangle
Below table helps us to understand how to find the perimeter of different triangles- Equilateral triangle, Isosceles triangle and Scalene triangle.

Perimeter of regular shapes
Perimeter of a parallelogram with Base, Height and an Angle
The perimeter of the parallelogram with base and height is given using the property of the parallelogram. If “b” is the base of the parallelogram and “h” is the height of the parallelogram, then the formula is given as follows:
According to the property of the parallelogram, the opposite sides are parallel to each other, and the parallelogram perimeter is defined as two times of the base and height.
Thus, the formula for the perimeter of a parallelogram is
P = 2 (b +h/cos θ)
where θ is the angle BAE, formed between the height and side of the parallelogram, i.e. AE and AB

2. Area of Rectangle and Regular Shapes

Area of Rectangle and Regular Shapes

Introduction to area,

The area of any shape is the number of unit squares that can fit in to it.The area can be defined as the amount of space covered by a flat exterior of a particular shape. It is measured in terms of the" number of" square units (square centimetres, square height, square bases, etc.)

 Area of the rectangle,

Description Area of rectangle is the number of unit squares within the boundary of the rectangle. Alternately, the space caught up within the border of a rectangle is called the area of the rectangle. One good illustration of a rectangle shape is the lines of unit length in your house. You can freely figure out how important space the bottom occupies by counting the number of penstocks. This will also help you determine the area of the cubic floor.region involved by a rectangle within its four sides or boundaries.

 A = lb

 How to Calculate the Area of a Rectangle

 Follow the way below to find the area

Step 1 Note the range of length and breadth from the given data

Step 2 Multiply length and breadth values

Step 3 Write the answer in square units

 Area of the square,

Area of a square is defined as the number of square units required to fill a square. In general, the area is defined as the region involved inside the boundary of a flat object or 2d figure. The dimension is done in square units with the standard unit being square measures (m2).
The area of square formula used for calculating the region involved, let us try using graph paper. You are needed to find the area of a side 5 cm. Using this dimension, draw a square on a graph paper having 1 cm × 1 cm squares. The square covers 25 complete squares.
Therefore, the area of the square is 25 square cm, which can be written as 5 cm × 5 cm, that is, side × side.
From the above discussion, it can be inferred that the formula can give the area of a square is
Area of a Square = Side × Side
Thus, the area of square = Side2 square units
And the perimeter of a square = 4 × side units

To find the area by counting the squares in the graph

The area of 1 full square can be taken as 1sq. unit.
Still, then the area can be considered as 1sq, if the region covers another than half the square. Unit.
Still, besides that region is neglected, if the region covers smaller than half the square.
Yet, also, the area is taken as 12sq, if the region covers exactly half the square. Unit.
These conventions are required to have in mind while chancing the area of the shape from the graph.
Sample
Find the area of the given shape by counting the squares.

 Answer

Let us count the number of squares.
Number of completely- filled squares = 6
Area of completely- filled squares = 6 × 1 = 6sq. cm
Number of half- filled squares = 2
 Area of half- filled squares = 2 × 12 = 1sq. cm
Number of further than half- filled squares = 4
 Area of other than half- filled squares = 4 × 1 = 4sq. cm
Number of lesser than half- filled squares = 2
 Area of smaller than half- filled squares can be neglected.
Total area covered by the given shape = (6 1 4) cm = 11sq. cm
Therefore, the total area covered by the given shape is 11sq. cm.

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