Find a parametric representation for the surface.
the part of the cylinder x² + z² = 49 that lies above the xy-plane and between the planes y = -8 and y = 8 (Enter your answer as a comma-separated list of equations. Let x, y, and z be in terms of u and/or v.)
________ where -8 ≤ u≤ 8, 0 ≤ ν ≤ π
