The sine rule how to find a missing side 

Thank you for your kind comment, let me know if I can help in anyway

I suppose in mathematics (Mathematical modelling vs real-life rounding) the value of 4 is taken as an accurate value of 4 eg it could be 4.0000000 Unless I specify the degree of accuracy of 4, this becomes less critical. Had I said it was 4 to 1 sf then your point would be absolutely valid. Good question though...