Mark M. answered 06/13/21
Retired math prof. Very extensive Precalculus tutoring experience.
To find the period: -π/2 < 7x - 56 < π/2 (one copy of the graph of y = tanx lies between -π/2 and π/2)
-π/2 + 56 < 7x < π/2 + 56
-π/14 + 8 < x < π/14 + 8
Period = (π/14 + 8) - (-π/14 + 8) = π/7