14) The acceleration at t = 1 for r(1) = 15i + 2In 1347 + 6 K A) a(1) = 201 + -j + 12k B) a(1) = 201 + 2j + 12k C) a(1) = 20i + -j - 12k D) a(1) = 20i - 2j - 12k Find the length of the indicated portion of the trajectory. 15) r(1) = (2cos t)i + (2sin t)j + 5tk, Osts n/2 A) 1331 B) /29L C) 29t 2 16) r(1) = (1 + 5t)i + (1 + 81)j + (2 - 2t)k, -1 st =0 A) 89 B) V93 C) 2417 D) 29 Find the curvature of the curve r(t). 17) r(t) = (8 + In(sec t))i + (3 + 1)k, -7/2