Proof that The Diagonals of a Rhombus are Perpendicular

In the previous post, we have proved the converse of the Pythagorean Theorem.  In this post, we will prove that the diagonals of a rhombus are perpendicular to each other. That is, if we have parallelogram ABCD with diagonal and , then is perpendicular to . What We Know A rhombus is a parallelogram with four […]
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Proof of the Converse of the Pythagorean Theorem

The Pythagorean Theorem states that if is a triangle right angled at , then, . The converse of the Pythagorean Theorem states that if holds, then triangle is a right triangle right angled at . This means that in order to prove the converse of the Pythagorean Theorem, we need to prove that in the […]
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Base Angles of Isosceles Triangles are Congruent

Proof is probably one of the most difficult concepts to teach in high school mathematics. In this short post, we are going to discuss a simple activity that can be used in teaching mathematical proofs in Geometry. First, we can use a rectangular paper, fold it in the middle, and cut through the diagonal. Of course, […]
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