Theorem – The line segment joining the mid-points of two sides of a triangle is parallel to the third side. Given: A triangle △ABC, in which D and E are mid points of sides AB and AC respectively. DE is joined. To prove: Line joining the mid points D and E (DE) is parallel to the third line […]

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 Theorem – Alternate Interior Angles are Equal  If a transversal intersects two parallel lines, then each pair of alternate interior angles are equal. Given: Two parallel Lines AB and CD, and PS be transversal intersecting AB at Q and CD at R. To Prove: Each pair of alternate interior angles are equal. i.e. ∠BQR = ∠CRQ and ∠AQR = ∠QRD […]

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Angles opposite to equal sides of an isosceles triangle are equal. Given: A isosceles triangle △ ABC in which AB = AC, andangles opposite to equal sides of triangle are ∠B and ∠C. To prove: We need to prove that ∠B and ∠C, are equal                           ∠B = ∠C. Construction: Draw the bisector […]

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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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Vertically Opposite Angles Theorem Vertical angles theorem or Vertically opposite angles theorem states that, If two lines intersect each other, then vertically opposite angles are equal. Given: In the above statement, given that two lines intersect each other, so let AB and CD are two lines intersect each other at O as shown in figure so […]

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   Hypotenuse of a triangle In geometry, the longest side of a right-angled triangle, the side opposite the right angle is known as hypotenuse. Pythagoras theorem applies to right triangles and states that,  The square on the hypotenuse is equal to the sum of the squares on the other two sides.  (hypotenuse)2   =    (Base)2+(Perpendicular)2    […]

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Quadrilateral – Definition – Properties There are kinds of quadrilaterals, based on the sides and angles.  1. Parallelogram 2  Rectangle 3. Square 4. Rhombus 5. Trapezium 6. kite 1.                       Parallelogram A Parallelogram is a quadrilateral, whose both pairs of opposite sides are parallel and equal in length. In above […]

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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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                 Additive Inverse Definition: In mathematics, the additive inverse of a number is what we add to a number to create the sum of zero.  So in other words, we can say that the additive inverse of x is -x, which is equal and opposite in sign to it. […]

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Vertical Angles When two lines are intersect they made four angles, angles are opposite to one another at the intersection of two lines. Each opposite pair of angles are called “Vertical Angles”, and vertical angles are always “Congruent” They are also called  “Vertically Opposite Angles”.                      In above […]

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