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prove that the tangent drawn at the end of an arc of a circle is parallel to the chord joining the end points of the arc |
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Answer» Given: A circle with Centre O, P is the midpoint of Arc APB. PT is a tangent to the circle at P. To Prove: AB || PT Construction: join OA ,OB, & OP Proof: OP ⟂PT [Radius is ⟂ to a tangent through the point of contact] ∠OPT = 90° Since P is the midpoint of Arc APB Arc AAP = arc BP ∠AOP = ∠BOP ∠AOM = ∠BOM In ∆ AOM & ∆BOM OA = OB = r OM = OM (Common) ∠AOM = ∠BOM (proved above)∠AOM ≅∠BOM (by SAS congruency axiom) ∠AMO = ∠BMO (c.p.c.t) ∠AMO + ∠BMO= 180° ∠AMO = ∠BMO= 90° ∠BMO = ∠OPT= 90° But, they are corresponding angles. Hence, AD||PT |
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