Important Formulas on Perimeter and Area
1. Perimeter of a rectangle = 2 ×
(length + breadth).
2. Perimeter of a square = 4 × length of
a side.
3. Perimeter of a triangle = sum of all
its sides.
4. Perimeter of a parallelogram = 2 ×
(length + breadth).
5. Perimeter of a rhombus = 4 × length
of a side.
6. The total distance around a circle is
called its circumference.
7. The circumference of a circle of
radius r is 2Ï€r.
8. The ratio of the circumference of a
circle to its diameter is denoted using the notation ‘Ï€’.
9. The approximate value of π is 22/7 or
3.14.
10. Perimeter of a regular polygon =
(Number of sides of polygon) × (length of a side).
11. Area of a rectangle = length ×
breadth.
12. Area of a square = side × side.
13. Area of a triangle = 1/2 × base ×
height.
14. The area of a circle of radius r is
Ï€r2.
15. Area of a parallelogram = base × perpendicular
height.
16. Area of a rhombus = 1/2 × product of
its diagonals.
17. Area of a trapezium = 1/2 × sum of
parallel sides × height.
18. Area of a quadrilateral = 1/2 × (one
diagonal) × (sum of the perpendiculars to the diagonal from the opposite
vertices).
19. Area of a polygon = Sum of the areas
of various triangles and trapeziums into which the polygon is splitted.
20. The units of area are square units,
such as 1 cm2 = 100 mm2 ; 1 m2 = 10,000 cm2
; 1 km2 = 10,00,000 m2 ; 1 hectare = 10,000 m2 ;
1 acre = 4046.86 sq. m.
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