## Thomas' Calculus 13th Edition

$s'=\frac{12}{3π}cos(3t)-\frac{4}{π}sin(5t)$
Take the derivative and apply chain rule: $s'=\frac{4}{3π}cos(3t)\times3-\frac{4}{5π}sin(5t)\times5=\frac{12}{3π}cos(3t)-\frac{4}{π}sin(5t)$