Important Formulas: Mensuration | Mathematical Reasoning and Aptitude for UGC NET PDF Download

(1) The size of a line segment is its length.
(2) The sum of lengths of all sides of a plane figure or the length of its boundary is called the perimeter of the figure
(3)The measurement of the region enclosed by a closed plane figure is called the 'area' of the plane figure.
(4) A square centimetre is the area of the region formed by a square of side 1 cm.
(5) Perimeter of a Square= 4 × length of a side = 4a 

Area of Square= Side × Side =Side²=a² 

(6) Perimeter of a Rectangle= 2× [length ( l ) + width (w)] 

Area of a Rectangle= length ( l ) × breadth ( b) 

(7) Perimeter of a Triangle= Sum of lengths of all sides = a + b + c. 

Area of triangle = (1/2) × base × height = (1/2) × b × h 

(8) Perimeter of an equilateral triangle = 3 × length of a side

(9) Perimeter of a Regular Pentagon= 5 × length of a side 

(10) Perimeter of a Regular Hexagon= 6 × length of a side 

(11) Perimeter of a Regular Octagon= 8 × length of a side 

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