14: Sine is 2π-periodic,
by the rules the given function should be
2π/3-periodic. There is no
general rule for absolute value, but the basic period of sine has the shape
of two hills, one up and one down, and the absolute value will flip the
lower hill up. Thus there is a possibility that the basic shape is in fact
half of the sine wave, in other words, we guess the basic period to be half
of what we had by rules:
T = π/3.
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Answer