Question

If the length of a rectangle is twice a breadth and perimeter is 60cm.find length ?

Answer 1

Answer:

length=2x

breath=x

perimeter=2 (l+b)

60=2 (2x+x)

60=2×3x

60=6x

x=60/6=6

length=10cm

breath=10×2=20cm

Answer 2

$\huge{\underline{\underline{\red{\mathfrak{Answer :}}}}}$

$\large \tt Given \begin{cases} \sf{Length \: = \: 2Breadth} \\ \sf{Perimeter \: = \: 60 \: cm} \end{cases}$

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$\setlength{\unitlength}{2cm}\begin{picture}(16,4)\thicklines\put(8,3){\circle*{0.1}}\put(7.8,3){\large{A}}\put(7.4,2){\mathsf{\large{10cm}}}\put(8,1){\circle*{0.1}}\put(7.8,1){\large{B}}\put(9.3,0.8){\matsf{\large{20cm}}}\put(11.1,1){\large{C}}\put(8,1){\line(1,0){3}}\put(11,1){\circle*{0.1}}\put(8,1){\line(0,2){2}}\put(11,1){\line(0,3){2}}\put(8,3){\line(3,0){3}}\put(11,3){\circle*{0.1}}\put(11.1,3){\large{D}}\end{picture}$

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Let Breadth be b

So,

Length = 2b

We know formula for perimeter of rectangle,

$\Large{\underline{\boxed{\sf{Perimeter \: = \: 2(l \: + \: b) }}}}$

Put Values

⇒60 = 2(2b + b)

⇒60 = 2(3b)

⇒60/2 = 3b

⇒30 = 3b

⇒3b = 30

⇒b = 30/3

⇒Breadth = 10 cm

And,

As length = 2Breadth

⇒length = 2(10)

⇒Length = 20 cm