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In the following figure O is the centre of the circle chord PQ and RS intersect inside the circle at M . Prove that: Angle POR + Angle QOS = 2Angle PMR. |
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Answer» Answer: O is the centre of the circle. chord PQ≅ chord RS (Given) ⇒ ARC PQ≅ arc RS (Correspondidng arcs of CONGRUENT chords of a circle are congruent) ⇒m(arcPQ)=m(arcRS) ⇒m(arcPQ)=80 o [m(arcRS)=80 o ] (1) m(arcPR)=∠POR=70 o (Measure of a minor arc is the measure of its central angle) (2) m(arcPR)+m(arcPQ)+m(arcQS)+m(arcRS)=360 o
⇒70 o +80 o +m(arcQS)+80 o =360 0
⇒m(arcQS)=360 o −230 o =130 o
(3) m(arcQSR)=m(arcQS)+m(arcRS)=130 o +80 o =210 o |
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