special rectangulars
Level
pending
how many integral rectangular such that its area equal to its circumference ?
The answer is 2.
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1 solution
Area = circumferernce
xy=2x+2y
xy-2y=2x
xy-2y=2x-4+4
y(x-2)=2(x-2)+4
y=2+(4/x-2)
y is integer so that
x-2 must equal to {1,2,4}
x-2=1 >>> x=3 >>> y=6
x-2=2 >>> x=4 >>> y=4
X-2=4 >>> x=6 >>> y=6
So that there is 2 rectangular 3×6 and 4×4