Question 519245
The sum of the interior angles of a polygon = (n-2)*180, when n = number of sides.
Given the polygon has four sides,
Then the four interior angles total (4-2)*180 = 2*180 = 360 degrees.
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Note a four-sided polygon is called a quadrilateral.
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Congruent angles are equal.
Given the angles are congruent,
Then the four interior angles are 360/4 = 90 degree each.
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A quadrilateral with four 90-degree interior angles is a rectangle.
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Done.