the figure O is the centre of the circle, OB=5cm ,distance from O to chord AB is 3cm. find the length of AB
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Here O is the centre of the circle
OB=5cm
Let the distance from O to AB is OD and OD=3cm
From the triangle ODB we have
OD^2+DB^2=OB^2
Or, (3)^2+DB^2=(5)^2
Or, DB^2=(5)^2-(3)^2
Or, DB^2=25-9
Or, DB^2=16
Or, DB=4
therefore AB=2×4=8 cm
OB=5cm
Let the distance from O to AB is OD and OD=3cm
From the triangle ODB we have
OD^2+DB^2=OB^2
Or, (3)^2+DB^2=(5)^2
Or, DB^2=(5)^2-(3)^2
Or, DB^2=25-9
Or, DB^2=16
Or, DB=4
therefore AB=2×4=8 cm
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