# NCERT Class 9 Maths Formula CBSE Board Sample Problems Part 11

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## 11. Heron Formula

S.no | Term | Description |

1 | Mensuration | It is branch of mathematics which ¡s concerned about the measurement of length ,area and Volume of plane and Solid figure |

2 | Perimeter | a)The perimeter of plane figure is defined as the length of the boundary b)It units is same as that of length i.e. m ,cm, km |

3 | Area | a)The area of the plane figure is the surface enclosed by its boundary b) It unit is square of length unit. i.e. |

**Unit Conversion**

1 Meter | 10 Decimeter | 100 centimeter |

1 Decimeter | 10 centimeter | 100 millimeter |

1 Km | 10 Hectometer | 100 Decameter |

1 Decameter | 10 meter | 1000 centimeter |

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 | 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 breadth L and B respectively | A=LX B | |

6 | Parallelograms Two sides are given as a and b | A= Base X height When the diagonal is also given ,say d Then W here | |

7 | Rhombus Diagonal d1 and d2 are given | ||

8 | Quadrilateral a) All the sides are given a, b, c, d b) Both the diagonal are perpendicular to each other c) When a diagonal and perpendicular to diagonal are given where d is diagonal and and are perpendicular to that | a) | a) Where b) Where and are the diagonal c) |