Number Line – Definition -Examples What is a Number Line? A number line is a straight line with representing numbers visually. A number line can be extended infinitely in any direction. A number line usually represent horizontally. In a number line, integers, decimals and fractions can also be represented easily. Number Line Definition A Number […]

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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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Angle Bisector – Definition -Examples  The angle(interior) bisector of an angle is a line or line segment that divides the angle into two (congruent)equal parts.  The angle bisector is also called the internal angle bisector. In ∠ABC, BD is angle bisector of ∠ABC. In above figure BD is bisect the ∠ABC. ∵ ∠ABC = 900∴ ∠ABD   = 450and ∠DBC = 450 ∠ABD and ∠DBC […]

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The line drawn through the center of a circle to bisect a chord is perpendicular to the chord. Given:  A circle with center O, AB is chord of a circle and OC bisect chord at C. i,e. AC = CB. To prove: OC ⊥ AB Construction: join OA and OB.  Proof:  In △ OCA and △ OCB OA = OB (Radius […]

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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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What is an Acute Triangle: Definition, Formula and Properties In geometry, a triangle is a polygon with three sides, three vertices and three interior angles. In other words a triangle is a closed two dimensional plane figure with three sides and three angles. Triangles are classified on the basis of their sides and angles. There […]

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Angle Formed By Two Lines and a Transversal  In above figure line l, intersects two lines m and n at the point p and q respectively. Therefore, line l is a “Transversal” for lines m and n. Four angles are formed at the points p, by line l, name of these angles as  ∠1, ∠2, ∠3, and ∠4. Four angles are formed […]

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