The function L(t) = 12 + 5.5 sin( 2/365 t) models the length of a day from

The function L(t) = 12 + 5.5 sin( 2π/365 t) models the length of a day from sunrise to sunset in Moscow, Russia, where t is the day in the year after the spring equinox on March 21. Determine L'(t), and use it to calculate the rate that the length of the days are changing on March 25, April 30, and June 10. Discuss what the results say about the changing day length in the spring in Moscow.