Radius of a circle is 18 cm. Angle made by chord AB at the centre of this circle is 60 degree. What is the length of this chord ?

18 cm

OA = OB = 18 cm.

\(\Delta \) OAB is an isosceles triangle.

So, \(\angle\)OAB = \(\angle\)OBA = \({(180\;-\;60)}^\circ\)/2

Since, \(\angle\)OAB = \(\angle\)OBA = \(\angle\)OAB = \({60}^\circ\),

\(\Delta \)OAB is an equilateral triangle.

So, OA = OB = AB = 18 cm

Therefore, the length of this chord is 18 cm.