A circle has radius 17 cm. A chord of the circle is 8 cm from the centre. How long is the chord?

Explanation

1. 01

   The perpendicular from the centre to a chord bisects the chord.

2. 02

   Half the chord = $\sqrt{17^2 - 8^2} = \sqrt{289 - 64} = \sqrt{225} = 15$ cm.

3. 03

   Full chord = $2 \times 15 = 30$ cm.