（5），9，。XY，，。。9-51：（3）
Take the cross center line (straight line and coordinate axis passing point 5)
as the benchmark, measure the coordinate values of 9 points in turn and
record. The measurement method is that one side of the vernier caliper
coincides with the X-axis or Y-axis of the cross center line, and the other side
coincides with the point to be measured. At this time, the reading is the
correction value. Or use the quadratic element measurement. As shown in
Figure 9-5, take the correction value of point 1 as an example: (it can be
considered that the method of measuring for three times to take the average
value, which will be more accurate)
4、5。2、3，4、5，。
Fill the measured values into columns 4 and 5 of the data table. In which, the
columns 2 and 3 are the set distances, and the columns 4 and 5 are the
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