In Fig. If OA=5 cm, AB=8 cm and OD is perpendicular to AB, then CD is equal to:
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In figure, if OA = 5 cm, AB = 8 cm and OD is perpendicular to AB, then CD is equal to
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asked Feb 1, 2018 in Class IX Maths by navnit40 (-4,939 points)
In figure, if OA = 5 cm, AB = 8 cm and OD is perpendicular to AB, then CD is equal to
(a) 2 cm
(b) 3 cm
(c) 4 cm
(d) 5 cm
circles
answer
2 Answers
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answered Feb 1, 2018 by aman28 (-872 points)
(a) We know that, the perpendicular from the centre of a circle to a chord bisects the chord.
AC = CB = 1/2 AB = 1/2 x 8 = 4 cm
given OA = 5 cm
AO2 = AC2 + OC2
(5)2 = (4)2 + OC2
25 = 16 + OC2
OC2 = 25-16 = 9
OC = 3 cm
[taking positive square root, because length is always positive]
OA = OD [same radius of a circle]
Step-by-step explanation:
2 cm