|AP| = |PB| = x (The perpendicular to a chord bisects the chord if drawn from the center of the circle.) From ∆OPB Using Pythagoras theorem ⇒ 132=122+x2 ⇒ 169=144+x2 ⇒ 169−144=x2 ⇒ x2=25 ⇒ x=√25=5cm ∴ Length of the chord |AB| = x+x=5+5=10cm
