### Mathematics Class IX

Number Systems
Polynomials
Coordinate Geometry
Lines and Angles
Triangles
Circles
Constructions
Heron’s Formula
Surface Areas and Volumes
Statistics
Probability

# Introduction

The area represents the amount of planar surface being covered by a closed geometric figure.

##### Properties of the Area of a figure
• If the shape and size of the two figures are the same then these are said to be congruent. And if the two figures are congruent then their area will also be the same. If ∆ABC and ∆DEF are two congruent figures then ar (∆ABC) = ar (∆DEF).
• But if the two figures has the same area they need not be congruent.
• If the two non-overlapping plane regions form a new planner region. Let Area of the square be ar(S) and Area of Triangle be ar (T). So Area of the new figure is Ar (P) = ar(S) + ar (T)
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