Length and Maximum angle?

Question

It is said that Galileo discovered a basic principle of the pendulum-that the period is independent of the amplitude-by using his pulse to time the period of swinging lamps in the cathedral as they swayed in the breeze. Suppose that one oscillation of a swinging lamp takes 5.5 s. How long is the lamp chain? What maximum speed does the lamp have if its maximum angle from vertical is 3.0 degrees?

Answer 1

a) 7.51m

L = g/(4 pi^2) * t^2

b)0.449m/s

h = L - Lcos(theta)
v = sqrt(2*g*h)