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A Chord of Lngth 6 Cm is at a Distance of 7.2 Cm from the Centre of a Circle. - Mathematics

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Question

A chord of length 6 cm is at a distance of 7.2 cm from the centre of a circle. Another chord of the same circle is of length 14.4 cm. Find its distance from the centre.

Sum

Solution

AF = FB = 3cm 

CE = ED = 7.2cm
(Perpendicular from centre to a chord bisects the chord) 

In right Δ AFO, By Pythagoras theorem, 

OA2 =OF2+ AF2 

OA2 = (7.2)2 + (3)2 

OA2 = 51.84 + 9 

OA2 = 60.84 

OA = 7.8cm 

OA = OC = 7.8cm         (radii of same circle) 

Similarly, In right Δ OFC, 

OC2 = OE2 + EC2 

OE2 = (7 .8)2 - (7.2)2 

= 60.84 - 51.84 

OE2 = 9 

OE = 3cm 

Distance from centre of chord CD with length 14.4cm is 3cm. 

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Chapter 17: Circles - Exercise 17.1

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Frank Mathematics - Part 2 [English] Class 10 ICSE
Chapter 17 Circles
Exercise 17.1 | Q 17
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