**1. The problem statement, all variables and given/known data**

**2. Relevant equations**

I have the solutions and how they did it. THey took the deriv for the velocity vector, and then using t=0 and t=14, they found e=3.5 and f=-0.125

**3. The attempt at a solution**

I understand the math, but I don’t understand why this is correct

1) why did they take the velocity vector?

2) if I plug e and f back into the position vector, and using t=14 i should get θ=0, ie, j-component is 0. But I don’t. So what am I doing wrong?

http://ift.tt/1jlF5jS