NCERT Exemplar Solutions
Class 6 - Mathematics - Unit 6: Mensuration - Problems and Solutions

Question 29

Step 1: What is perimeter?
Perimeter means the total length around the outer boundary of a figure. We only add the outer edges, not the lines inside.

Step 2: Look at the outline only.
The inside is made of many smaller equilateral triangles (made by joining midpoints), but these do not change the outside boundary. So we will trace only the outside.

Step 3: Count the outer sides.
The outline forms 6 equal outer sides (like a hexagon made from equilateral triangles).

Step 4: Find the length of one outer side.
Each outer side is a full side of the original equilateral triangle. Given (AB = 8) units, every full side on the boundary is also 8 units.

Step 5: Add all the outer sides.
Number of boundary sides: (;6;)
Length of each side: (;8 ext{units};)
Perimeter: (;6 imes 8;)

Step 6: Calculate.
(;6 imes 8 = 48 ext{units};)

Perimeter of the figure = 48 units

Tip: Don’t add any inside segments. They help form smaller triangles but don’t add to the outside length.