A chord of circle of radius 7cm is 5cm from the... - JAMB Mathematics 2011 Question

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