A chord of length 8 cm is drawn at a distance of 3 cm from the centre of a circle. Calculate the radius of the circle.
5 cm
In the circle, O is the centre chord AB = 8 cm.
OM ⊥ AB which bisects it at M.
∴ AM=12 AB=12×8=4 cm
OM = 3 cm
Now in right Δ OAM,
OA2=AM2+OM2
=(4)2+(3)2=16+9=25
∴ OA=√25=5 cm