Find the length of the segment CD1 if D (2.8), CD = 1.4, and points D and D1 have opposite coordinates.

1) Find the coordinate of point C.
Since the segment CD has a length of 1.4, and point D – coordinate (2.8), then point C will have coordinate (1.4). Segment Co = CD = 1.4.
Then CD1 = | -2.8 | + | 1.4 | = 2.8 + 1.4 = 4.2.
Answer: CD1 = 4.2.
2) Determine the length of the segment CD. Point C now has a coordinate (-1,4), then:
CD = | -2.8 | – | -1.4 | = 2.8 – 1.4 = 1.4.
The segments DC and Co are equal and have a length of 1.4.
Then the length of the segment CD1 = | -1.4 | + | 2.8 | = 1.4 + 2.8 = 4.2.
Answer: CD1 = 4.2.