11. A rectangle's length is 5 cm less than twice
its width. If the length is decreased by 5 cm
and width is increased by 2 cm; the perimeter
of the resulting rectangle will be 74 cm. Find
the length and the width of the original
rectangle
Answers
Answer:
Length=25cm
Width=15cm
Step-by-step explanation:
Let width of the original rectangle = x cm
Length of the original rectangle = (2x – 5)cm
Now, new length of the rectangle = 2x – 5 – 5 = (2x – 10) cm
New width of the rectangle = (x + 2) cm
New perimeter = 2[Length+Width] = 2[2x – 10 + x + 2] = 2[3x – 8] = (6x – 16) cm
Given; new perimeter = 74 cm
6x – 16 = 74
=> 6x = 74 + 16
=> 6x = 90
=>x = 15
Length of the original rectangle = 2x – 5 = 2 x 15 – 5 = 30 – 5 = 25 cm
Width of the original rectangle = x = 15 cm
let s take,
length = x
breadth = x
length is 5cm less than twice it's width
breadth = x
length = 2x - 5
if the length is decreased by 5cm and width is increased by 2cm
length = 2x - 5 - 5 = 2x + 10
breadth = x + 2
perimeter of rectangle = 74 cm
2 ( l + b ) = 74
2 ( 2x + 10 + x + 2 ) = 74
2 ( 3x + 12 ) = 74
6x + 24 = 74
6x = 74 - 24
6x = 60
x = 60 / 6
x = 10
length = 2x + 10 = 2(10) + 10 = 20 + 10 = 30
breadth = x + 2 = 10 + 2 = 12
Hence,
length = 30cm
breadth = 12cm
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