Answers

The Brainliest Answer!
2016-01-12T12:53:52+05:30
Draw the figure. points B and C must both be on the circle. Now connect both points B and C to the circle center O. 
Since both AB and AC are tangent to the circle then AB = AC 
Now draw the line AO 
<OAB and <OAC are equal. 
Since BAC = 120 
<OAB = 60 and <OBA = 90 deg and therefore <AOB is 30 deg. 
So sin<AOB = sin 30 = 1/2 = AB/ OA and 
OA = 2 AB

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figure and proof is also given in below attached pic
2 5 2
2016-01-12T14:59:48+05:30