Perimeter and Area - Revision Notes

 CBSE Class–VII Subject Mathematics

Revision Notes

Chapter –11

Perimeter and Area

• ---

  Perimeter is the distance around a closed figure whereas area is the part of plane occupied by the closed figure.
• Area is the measure of the part of plane or region enclosed by it.
• We have learnt how to find perimeter and area of a square and rectangle in the earlier class. They are:
  (a) Perimeter of a square = 4 × side
  (b) Perimeter of a rectangle = 2 × (length + breadth)
  (c) Area of a square = side × side
  (d) Area of a rectangle = length × breadth
• Area of a parallelogram = base × height
• Area of a triangle = 12$\frac{1}{2}$(area of the parallelogram generated from it)
  
• Area of equilateral triangle = 
• The distance around a circular region is known as its circumference.
• The ratio of circumference and diameter of a circle is a constant is denoted by (pi).
• Circumference of a circle = πd, where d is the diameter of a circle and π=227 or 3.14$\pi =\frac{22}{7}or3.14$ (approximately).
• Area of a circle,  where r is the radius of the circle.
• Based on the conversion of units for lengths, studied earlier, the units of areas can also be converted: