Q5 of 23 Page 274

In the figure, ‘O’ is the centre of the circle. OM = 3cm and AB = 8cm. Find the radius of the circle

Joining OA we see that OA is radius of the circle.


Let radius (OA) be r cm.


Given, AB = 8cm


OM = 3cm


We know that “perpendicular from center divides the chord into equal parts”.


AM =


⇒ AM = 4 cm


In right angled triangle OAM,


OA2 = OM2 + AM2 (Pythagoras Thm.)


⇒OA2 = 32 + 42


⇒OA2 = 9 + 16


⇒OA2 = 25


⇒OA =


⇒OA = 5 cm


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