Question 887180
x for the side length of the square, and y for side length of the triangle.
{{{y=x+7}}}, from description.


Perimeters of the square and the equilat. triangle are equal.
{{{4x=3(x+7)}}}  ------ Think of this carefully.


When that makes sense, just solve it for x, and use this to compute y.




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x=21,    y=28