Co-internal angles Co-interior angles, also known as consecutive interior angles or same-side interior angles, are pairs of angles that lie on the same side of a transversal and inside the two lines it intersects. These angles have specific properties depending on whether the lines they intersect are parallel or not. Definition and Identification (1) Transversal […]

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What is an Angle Angles are formed by two rays or lines called the arms or sides of the angle, sharing a common endpoint, called the vertex of the angle. Types of angles There are various types of angles. The angles can be classified into two main types. Basis on their measure or magnitude. Based […]

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 Parallelograms – Properties   A parallelogram is a special type of a polygon. it is a quadrilateral with both pair of opposite sides are parallel. Properties 1. Opposite sides are equal.       Opposite sides, AB = CD and AC = BD 2. Opposite angles are equal.      Opposite angles are ∠A = ∠D and ∠B […]

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The sum of the angles of a triangle is 180º Given: A triangle △ PQR and ∠1, ∠2, and ∠3 are angles of triangle △ PQR.  To prove:  ∠1 + ∠2 + ∠3 = 1800 Construction: Draw a line XPY parallel to QR passing through P.  Proof: XPY ∥ QR and PQ is transversal ∴ ∠2 = ∠4 (Alternate angles) ….(1) XPY ∥ QR and PR […]

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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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Concave Polygons: Definition – Examples & Properties   All polygons is either convex or concave. A polygon will be convex or concave, it depends on the measure of their angles. What is a Concave Polygon? A concave polygon have at least four sides, and concave polygon is just opposite of a convex polygon. If the measures […]

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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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Triangle – Definition and Properties The origin of term “Triangle” from latin word tri (“Three”) and angulus means (“angles”). A “Triangle” is a simple closed curve or a three sided polygon. A triangle has three angles and three sides and three vertices. It is one of the basic shape in geometry.   In Euclidean geometry any non-collinear, three points, determine a unique triangle.  The triangle […]

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