Question 571359
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The key phrase in the question is "must be"


You don't know anything about the relative measures of the adjacent sides, so while the figure certainly <i><b>could</b></i> be a square, or a rhombus for that matter since a square is just a special case of the rhombus, the congruence of adjacent angles demands that the quadrilateral be at least a rectangle.


In fact, your quadrilateral <i><b>could</b></i> be a trapezoid because there is some disagreement on the allowed number of parallel sides in a trapezoid. At issue is whether parallelograms, which have two pairs of parallel sides, should be counted as trapezoids. Some authors define a trapezoid as a quadrilateral having exactly one pair of parallel sides, thereby excluding parallelograms. Other authors define a trapezoid as a quadrilateral with at least one pair of parallel sides, making the parallelogram a special type of trapezoid (along with the rhombus, the rectangle and the square). The latter definition is consistent with its uses in higher mathematics such as calculus. The former definition would make such concepts as the trapezoidal approximation to a definite integral ill-defined.


John
*[tex \LARGE e^{i\pi} + 1 = 0]
My calculator said it, I believe it, that settles it
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