Question 1132292
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(1) The area of the small square is half the area of the large square.  (You can see this by drawing just the two squares and then drawing the diagonals of the small square.) So the side length of the small square is {{{a/sqrt(2)}}}.<br>
(2) The side length of the small square is the diameter of the circle.<br>
(3) Obviously the radius of the circle is half its diameter.<br>
(4) By drawing the three altitudes of the equilateral triangle (dividing the triangle into 6 congruent 30-60-90 right triangles), you can determine that the side length of the triangle is (sqrt(3)/2) times the radius of the circle.<br>
Put all those part together to find the side length of the triangle; then the area of an equilateral triangle with side length s is {{{s^2*sqrt(3))/2}}}<br>