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In the adjoining figure, BD is the diameter of the circle which bisects the chord AC at point E. If `AC=8cm`, `BE=2cm`, then find the radius of the circle. |
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Answer» Let radius `OA=OB =r` `OE=OB-EB` `=(r-2)cm` `AE=(AC)/(2)=(8)/(2)=4cm` Now, `angle OEA=90^@` (`because` The line segment joining the centre to mid-point of a chord is perpendicular to the chord) `therefore` In `DeltaOAE`, `OA^2=OE^2+AE^2` (by Pythagoras theorem) `rArrr^2=(r-2)^2+4^2` `rArrr^2=r^2-4r+4+16` `rArr4r=20 cm` `rArr=5cm` `therefore` Radius of circle =5 cm . |
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