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
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.
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
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 |