Question

the length of rectangle is three times its width. if perimeter is 84 cm fund the length of rectangle​

Answer 1

Answer:

let the width be x

so length is 3x

perimeter of rectangle = 2(l+b)

84 = 2(x + 3x )

84= 2(4x)

84 = 8x

84/8 = x

10.5 =x

breadth = 10.5 cm

length = 31.5 cm

Answer 2

Answer:

Given, l=3b ... (1)

2(l+b)=84

2(4b)=84 ......from(1)

b=84/8=21/2=10.5cm

l=3×21/2=63/2=31.5cm