Using Laplace Transform to solve a differential equation

[november1992]

Homework Statement

y" + y = 4δ(t-2π); y(0)=1, y'(0)=0

Homework Equations

L[f(t-a) U(t-a)] = e^{-as} L[f(t)]

L[δ(t-c)] = e^{-cs}

The Attempt at a Solution

My answer is: cos(t) + 4U(t-2π)sin(t-2π).

When I used Wolframalpha it gave me 4sin(t)U(t-2π) + cos(t)

 

[I like Serena]

Hi november1992!

So what is your question?

Did you know that sin(t-2π)=sin(t) since the sine has a period of 2π?

 

[november1992]

I meant to ask why is my answer different. I don't remember any of the trig identities so I'll have to review them.

Thanks for answering my question!