A wind turbine has blades 10 meters long and a tower 38 meters high. The turbine rotates at a rate of 2 radians every 3 seconds. One of the turbine's blades is in the 3 o'clock position the instant the turbine begins moving. Define a function f that gives the distance of this blade's tip above the ground (in meters) as a function of t, the number of seconds that have passed since the turbine began moving.

 

Determine algebraically the number of seconds that have passed during the turbine's first revolution that the tip of the blade will be 40 m above the ground. (Round your answers to four decimal places. Separate multiple solutions with a comma.)

​