r differential equation

Second order differential equation.
I want to convert this second order diff equ to a set of two first order.
d^2thata/dt^2 +(g/L)sin(theta) = 0, theta(0)=pi/6, theta'(0)=0
g = 32.17 ft./sec^2, L=2ft
Something like this:
u1(t) = theta(t)
u2(t) = theta'(t)
u1′(t) = u2(t)
u2′(t) = -16.085*sin(t) ??? not right

"Looking for a Similar Assignment? Order now and Get 10% Discount! Use Code "Newclient"