Find the limit as x approaches 0 of x/sin3x

What is the value of r of the geometric series?

Sanya noticed that the temperature was falling at a steady rate of 1.4 degrees every hour from the time that she first checked her outdoor thermometer. by 6 a. m., the temperature had fallen 21 degrees. which expression can you use to find how many hours earlier she had first checked the thermometer?

How do i start to solve? would appreciate a walk-thru! a bird sitting 16ft above the ground in an apple tree dislodges an apple. after how many seconds does the apple land on the ground? (assuming that no branches will interfere with it's fall)