The simple answer is that out of all the answer choices, the area of a circle that has Chord XY can vary. It all depends on the placement of Chord XY within the Circle.
Chord XY can be Length 4.
Case 1: chord XY is the Diameter of the Circle. The Circle’s Area is less than the area of the Circle in Case 2
Case 2: Chord XY connects 2 opposite-side Points of the Circle that are closer to the Circle’s perimeter.
In this Case 2, the chord XY is NOT the Diameter. The Case 2’s Diameter is greater than the Diameter of the Circle in case 1 —->thus the Area is greater (and most importantly different)
Why the other answers are wrong:
-A-
If the Circle’s diameter = XY, then the Circle and its corresponding Circumference will be fixed around the Diameter. Can not change.
-B-
If the Diagonal of the Square is XY, then the Square’s Area is fixed around the 2 Congruent Diagonals Equal to Length XY that are Perpendicular Bisectors of each other. Can not change.
-C-
The Right Isosceles Triangle always has its 3 Side lengths fixed based on a constant Ratio. Given the Side Length of 1 of the Legs (in which both Legs have equal lengths), the Perimeter of the Figure is fixed. Can not change.
-E-
An equilateral triangle has all 3 of its sides of equal length. Given 1 side length XY, we therefore know all 3 Side Lengths of the triangle. The figure’s area becomes fixed once the Side Lengths are known. Can not change.
Answer -D-
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