(18) Two internal angles of a triangle have been measured; A=72 36' 14" and B=5718'26", their standard deviations are ma=mg=15". Please calculate the third internal angle C and its standard deviation me. (19) A line segment has been measured six times using a steel tape. The observation values are shown in Table 7. 8. Please calculate the arithmetic mean of Dis: the standard deviation of the observation values (m), the standard devia- tion of the arithmetic mean (M); and the accuracy ratio (K). Table 7.8 Original data for exercise (19) D/m No. V/mm V Answers 1 210.735 DAR 2 210.773 3 210.748 4 210.750 5 210.720 M- 6 210.746 K (18) Two internal angles of a triangle have been measured; A=72 36' 14" and B=5718'26", their standard deviations are ma=mg=15". Please calculate the third internal angle C and its standard deviation me. (19) A line segment has been measured six times using a steel tape. The observation values are shown in Table 7. 8. Please calculate the arithmetic mean of Dis: the standard deviation of the observation values (m), the standard devia- tion of the arithmetic mean (M); and the accuracy ratio (K). Table 7.8 Original data for exercise (19) D/m No. V/mm V Answers 1 210.735 DAR 2 210.773 3 210.748 4 210.750 5 210.720 M- 6 210.746 K