In the adjoining figure, AB and CD are two parallel chords and O is the centre. If the radius of the circle is 15 cm, find the distance MN between the two chords of length 24 cm and 18 cm respectively.
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Solution
In the figure, chords AB ∥ CD
O is the centre of the circle
Radius of the Circle = 15 cm
Length of AB = 24 cm and CD = 18 cm
Join OA and OC
AB = 24 cm and OM ⊥ AB
AM = MB= 242=12 cm
Similarly ON ⊥ CD
CN = ND =182 = 9 cm
Now, In right ∆ CMO OA2 = AM2 + OM2 (15)2 = (12)2 + OM2
225 = 144 + OM2
OM2 = 225 – 144 = 81 = (9)2
OM = 9 cm
Similarly, In right ∆ CNO OC2 = CN2 + ON2 (15)2 = (9)2 + ON2
225 = 81 + ON2
ON2 = 225 – 81 = 144 = (12)2
ON = 12 cm
Now MN = OM + ON = 9 + 12 = 21 cm