Octagon – Definition, Types, Formula, Properties, Examples What is an Octagon ? An octagon is a geometric shape that has eight sides and eight angles. The word “octagon” comes from the Greek words “okto,” meaning eight, and “gonia,” meaning angle. Here are some key characteristics of an octagon. Definition: An octagon is a polygon with […]

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Lines of symmetry in a regular Rhombus What is a Rhombus? A rhombus is a quadrilateral whose all the sides are of equal in length, opposite sides are parallel and opposite angles are equal. In other words, a rhombus is a parallelogram with adjacent sides of equal length. What is line of symmetry ? The […]

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Two triangles on the same base (or equal bases) and between the same parallels are equal in area. Given: △ ABC and △ PBC are two triangles on same base (or equal bases) BC and between the same parallels, BC and AP. To prove: ar △ ABC = ar △ PBC Construction: Through B, draw BD ∥ CA intersecting PA produced at D, and […]

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 Rhombus – Definition – Properties Definition: A rhombus is a quadrilateral (closed shape, plane figure) with four straight sides that are equal length also opposite sides are parallel and opposite angles are equal. A rhombuses is a type of parallelogram. All rhombuses are parallelograms, but not all parallelograms are rhombuses.  All squares are rhombuses, but not all […]

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 Convex Polygons: Definition – Examples and Properties   All polygons is either convex or concave. A polygon will be convex or concave, it depends on the measure of their angles. If the measures of all interior angles is less 1800 than the polygon is convex, otherwise the polygon is concave.                 […]

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 Theorem : In a parallelogram, opposite angles are equal.  Given: A parallelogram ABCD,  opposite sides of parallelogram are                         side AB and side DC                         side AD and side BC. To prove: Opposite angles of parallelogram are equal. […]

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A diagonal of a parallelogram, divides it into two congruent triangles. Given: A parallelogram ABCD and AC is a diagonal, the diagonal AC divides parallelogram ABCD into two triangles △ ABC and △ CDA. To prove: These triangles △ ABD and △CDA are congruent,                        △ ABC ≅ △ CDA Proof: In △ ABC and △ CDA BC ∥ AD and AC […]

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If each pair of opposite sides of a quadrilateral is equal, then it is a parallelogram.  Given: ABCD is a quadrilateral, each pair of opposite sides of quadrilateral ABCD are AB and CD and also sides AD and BC are equal. AB = CD BC = AD To prove: ABCD is a parallelogram. Construction: Join A to C that is AC, is […]

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 In a parallelogram opposite sides are equal.  Given: A parallelogram ABCD, each pair of Opposite sides of parallelogram are side AB and side DC and side AD and side BC. To prove: Opposite sides of parallelogram are equal that is AB = DC    and    AD = BC  Construction: Join A to C that is AC, is a diagonal, the diagonal AC […]

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Properties of a Rectangle A rectangle is a two dimensional four sided polygon(quadrilateral), in which the opposite sides are equal and parallel to each other and all four angles are right angles. In figure ABCD is a rectangle.   Properties of a Rectangle A rectangle is a quadrilateral. 1. Each interior angle is a right angle. 2. […]

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