Class 6 Maths Mensuration Regular Closed Figures

Regular Closed Figures

Figures having all the sides of equal length and all the angles of equal measure are known as regular closed figures. Therefore a square and an equilateral triangle are regular closed figures.

 

Problem: Find the perimeter of each of the following figure:

Solution: 

Perimeter = Sum of all Sides

                 = 1 + 1 + 4 + 4 + 0.5 + 0.5 + 2.5 + 2.5 = 2+8+1+5

                = 16 cm

 

Problem: What is the length of the wooden strip required to frame a photograph of length and breadth 32 cm and 21 cm respectively?

Solution: The length of wooden strip is given by the perimeter of the photo frame as perimeter is the sum of all sides. Since the photo frame is rectangular in shape, its perimeter is :

 Perimeter = 2(length + breadth)

 Here, length = 32 cm and breadth = 21 cm

 Perimeter = 2(32 + 21)

                = 2(53)

                = 106 cms

Therefore, the length of wooden strip required is 106cms.

 

Problem: The perimeter of a regular pentagon is 100 cm. How long is its each side? 

Solution: Pentagon is a polygon with five sides of equal length.

Perimeter = Sum of all sides = 5a

Thus, 5a = 100 cm

            a = 100/5 = 20 cm

Therefore, the length of each side of a pentagon is 20 cm

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