A surveyor measures the distances between three markers, AAA, BBB, and CCC, placed on a plot of land. The distance AB AB\,AB is 6.4 m, the distance BC BC\,BC is 5.5 m, and the distance AC AC\,AC is 8.1 m.
Work out the size of angle BACBACBAC.
Give your answer to 3 significant figures.
