1.

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

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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