Draw a rectangle of perimeter 30cm and length of sides in the ratio 1:2.draw two more rectangles of the same perimeter with the length of sides in the ratio 2:3 and 3:7 compute the areas of all three rectangles?

4 answers

I will do the first one, you do the other two in the same way.

let the width be x
let the length be 2x, notice x : 2x = 1 : 2

2(x) + 2(2x) = 30
5x = 30
x = 6
sides are 6 cm and 12 cm, with an area of 72 cm^2
good job, except that 2(6+12) = 36, not 30

Should have been

2(x) + 2(2x) = 30
6x = 30
x = 5
sides are 5 cm and 10 cm, with an area of 50 cm^2, and a perimeter of 2(5+10) = 30
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Perimeter=30 cms
Ratio of sides=2:3
Breadth=2+3=5 cms
=(2÷5)×30=2×30=60÷5=12 cms
=12÷2=6 cms is the breadth
Length=3×30=90÷5=18 cms
=18÷2=9 cms is the length