Answer : -6
The common difference of a sequence is the value that changes every time the sequence continues.
In your sequence it is seen that 6 is subtracted from each term in order to get to the next in the sequence.
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Since one side is 40°, you subtract that from 180.
180° - 40°= 140°.
So therefore your missing side lengths are 140, 40, and 140.
hopefully this helps
