In the adjoining figure, OD is perpendicular to the chord AB of a circle whose centre is O. If BC is a diameter, then which of the following are true?
AC=2 OD
ACDO=BCBO
OD∥AC
AB is the chord and OD⊥AB ⟹ BD = AD (Since, perpendicular from the centre to a chord bisects the chord)
In △ABC, D is the mid-point of AB and O is the mid-point of BC.
∴OD∥AC
Now, in △ABC OD∥AC.
Then by BPT, we must have
ACDO=BCBO or ACDO=2BOBO=2
or AC=2 DO
i.e., AC=2 OD