NCERT Class 9 MathematicsHerons Formula (Mensuration) Board Sample Problems

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Mensuration

It is branch of mathematics which is concerned about the measurement of length, area and Volume of plane and Solid figure

Perimeter

The perimeter of plane figure is defined as the length of the boundary

It units is same as that of length i.e. m, cm, km

The perimeter of plane figure is defined as the length of the boundary

1 Meter

10 Decimeter

100 centimeter

1 Decimeter

10 centimeter

100 millimeter

1 Km

10 Hectometer

100 Decameter

1 Decameter

10 meter

1000 centimeter

Area

The area of the plane figure is the surface enclosed by its boundary

It unit is square of length unit. i.e.

The area of the plane figure is the surface enclosed by its boundary

1 square Meter

100 square Decimeter

10000 square centimeter

1 square Decimeter

100 square centimeter

10000 square millimeter

1 Hectare

100 square Decameter

10000 square meter

1 square myraimeter

100 square kilometer

square meter

Perimeter and Area of different figure

Perimeter and Area of different figure

N

Shape

Perimeter/height

Area

1

Right angle triangle Base =b, Height =h Hypotenuse=d

P

Height =h

2

Isosceles right angled triangle Equal side =a

Height=a

3

Any triangle of sides a ,b, c

Where

This is called Heron’s formula (sometimes called Hero’s formula) is named after Hero of Alexandria

4

Square Side =a

P=4a

5

Rectangle of Length and breath L and B respectively

P=2L+2B

6

Parallelograms Two sides are given as a and b

P=2a+2b

When the diagonal is also given, say d

Then

Where

7

Rhombus Diagonal and are given

8

Quadrilateral

a) All the sides are

b) Both the diagonal are perpendicular to each other

c) When a diagonal and perpendicular to diagonal are given

a) P

a)

Where

b)

where and are the diagonal

c)

where d is diagonal and and are perpendicular to that