This was another popular question among the candidates.  Most of them were able to state the correct formula and substituted correctly.  However, few had difficulty in handling sin =   to obtain the value of .  Some candidates manipulated sin 2  =  0.866 and got sin  =  0.433 which was wrong.  Some could not determine the arc sine (sin-1) of the number to arrive at the correct answer.  Few candidates failed to write unit while some gave wrong unit.

The expected answer is