Let's draw the isosceles trapezoid ABCD, where AD ≅ BC, and mADC ≅ mBCD.
If we draw the diagonals AC and BD of the trapezoid two congruent triangles are formed,
∆ ADC ≅ ∆ BDC (SAS Postulate: If two sides and the angle between them in one triangle are congruent to the corresponding parts in another triangle, then the triangles are congruent).
Since these triangles are congruent, AC ≅ BD.
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prove any two adjacent triangles as congruent
Suppose that the parallelogram is a rhombus (a parallelogram with equal sides). If we draw the diagonals, isosceles triangles are formed (where the median is also an angle bisector and perpendicular to the base). Since the diagonals of a parallelogram bisect each other, and the diagonals don't bisect the vertex angles where they are drawn, then the parallelogram is not a rhombus.
A ruler or a compass would help or aternatively use Pythagoras' theorem to prove that the diagonals are of equal lengths
You can't. A trapezoid is a quadrilateral because it has four sides. The definition of a quadrilateral is a shape with four sides.
it would produce two right angle triangleImproved Answer:-Measure them and use a protractor which will result in equal measures of 4 by 90 degrees angles