In the circle shown below AB is the chord having length 8 cm and being bisected by the line OD from centre. If the radius of circle is 5 cm, then find the distance of OD.
Here OD is bisecting AB, so AD = DB = 4 cm.
∠ODB=90∘ [Line through center that bisect the chord is perpendicular to chord]
So, OB2=OD2+DB2 [∵ ODB is right angled triangle]
OD2=OB2−DB2
OD2=(5)2−(4)2 [OB is radius]
OD2=25−16
OD2=9
OD = 3 cm