From Pythagoras theorem
|OA|² = |AN|² + |ON|²
7² = |AN|² + (5)²
49 = |AN|² + 25
|AN|² = 49 - 25 = 24
|AN| = \(\sqrt {24}\)
= \(\sqrt {4 \times 6}\)
= 2√6 cm
|AN| = |NB| (A line drawn from the centre of a circle to a chord, divides the chord into two equal parts)
|AN| + |NB| = |AB|
2√6 + 2√6 = |AB|
|AB| = 4√6 cm