trig with hours of daylight, days after equinox

At a certain latitude in the northern hemisphere, the number *d *of hours of daylight in each day of the year is taken to be *d*=*A*+*B*sin*kt*°, where *A*, *B, k *are positive constants and *t *is the time in days after the spring equinox.

Assuming that the number of hours of daylight follows an annual cycle of 365 days, find the value of *k*, giving your answer correct to 3 decimal places.

Ok I'm not really sure where to start here, any hints would be appreciated.

Am I supposed to use -1<sin*kt°*<1 ? how to i fit in the 365 day with *t?*