Idont understand how to do these three questions

Suppose a pendulum is l meters long. the time, t,in seconds that it tales to swing back and forth once is given by t=2.01

Asailor is looking at a kite. if he is looking at the kite at an angle of elevation of 36and the distance from the boat to the point where the kite is directly overhead is 40 feet, how high is the kite?

Find the center and the radius of the circle with the equation: x^2-2x+y^2+4y+1=0?