If two Lines are parallel to a third line then the lines are parallel to each other. Given: It is given that three lines l, m, and n, and line l ∥ line m and line m ∥ line n. To Prove:    Line l ∥ Line n Proof: Let us draw a line p transversal for lines l, m, and n. For lines l […]

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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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What is Theorem in Mathematics     In mathematics a theorem is a statement, that has been proved to be true on basis of facts that were already known and used in previously established statements.  The process of showing a theorem to be (true) correct is called proof. proofs are an important part of mathematics. […]

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The angle at the centre of a circle is twice the angle at the circumference, when both are subtended by the same arc.  Given: A circle with centre at O, arc BC of this circle subtends angles ∠BOC at centre O and ∠BAC at a point A remaining part of the circle.   To Proof: ∠BOC […]

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Prove that the angle in a semicircle is a right angle                           or Angle subtended by a diameter/Semicircle on any circle on any point of circle is 90º. Given: A circle O with centre O. BC is the diameter of circle subtending ∠BAC at […]

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If the diagonals of a Quadrilateral, bisect each other then that Quadrilateral is a Parallelogram Given: ABCD is a quadrilateral with AC and BD are diagonals and diagonals intersect each other at O. i.e. OA = OC and OB = OD To Prove: ABCD is a parallelogram. Proof: In △AOD and △COB           […]

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