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Xin Yi asked in Math

How to do f and question 4?find angle COD for question 4.

4. In the figure, AB is a tangent to the circle with centre O, D is the mid point of the chord BC. 



Given the  BAC=xo, find 
 COD in terms of x. 


 
 

Thank You
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Varun Rawat answered this

In ODC and ODBODC = ODB  90° each      OC = OB  radii of same circle      OD = OD    commonODC ODB   RHSCOD = BOD  CPCTBOC = 2CODNow, BOA + BOC = 180°  Linear pairBOA +  2COD = 180°BOA = 180° - 2COD In OBAOAB + BOA + OBA = 180°  Angle sum propertyx + 180°- 2COD  + 90° = 180°x + 90° = 2CODCOD =x2 + 45°