Page 183 - Math_Genius_V1.0_C6_Flipbook

E:\Working\Focus_Learning\Math_Genius-6\Open_Files\09_Chapter_6\Chapter_6
\ 07-Nov-2024 Bharat Arora Proof-8 Reader’s Sign _______________________ Date __________

Example 6: A rectangle with sidelengths of 15 cm and 9 cm is made using a piece of wire. If the
wire is straightened and then bent to form a square, what will be the length of a side of the square?

Solution: 15 cm

9 cm Rectangle Rebent Square ? cm

Perimeter of a rectangle = 2 (length + breadth)
= 2 × (15 cm + 9 cm) = 48 cm

So, the total length of the wire is 48 cm which is bent to form a square.
48
∴ The length of each side of the square = cm = 12 cm
4
 Perimeter of a square
  Q Length of side = 4  

Maths Talk
Gopal challenged Rahul to draw a triangle with a boundary length of 12 units by connecting dots
on a square dotted paper.

Rahul, how will you
draw a triangle of
perimeter 12 units?
I think this is the
triangle with its
perimeter 12 units.

What do you think about the triangle drawn? Will the perimeter be 12 units? Discuss with your friends.

Practice Time 6A

1. Find the perimeter of the rectangles having the following dimensions:
(a) Length = 16 cm; Breadth = 10 cm (b) Length = 28 cm; Breadth = 16 cm
2. Find the perimeter of the squares whose sides measure is:
(a) 15 cm (b) 11 m

3. Find the perimeter of the following figures:
(a) An equilateral triangle with a side of 10 cm. (b) A triangle with sides 16 cm, 8 cm and 12 cm.
(c) An isosceles triangle with two equal sides of 8 cm and the third side of 10 cm.
(d) A regular hexagon with a side of 17 cm.
4. Find the perimeter of each of the following regular polygons. Who has the largest perimeter?
(a) An equilateral triangle with a side of 18 cm. (b) A square with a side of 15 cm.

(c) A regular pentagon with a side of 9 cm. (d) A regular hexagon with a side of 8 cm.
5. Priya wants to seal the lid of a rectangular box with tape. Find the length of the tape required, if the
length and breadth of the lid are 2 m 15 cm and 2 m 25 cm, respectively.

181
181 Perimeter and Area
and Ar
ea
P
erimeter