# Simple Laplace trasfrom

1. Nov 18, 2012

### Mdhiggenz

1. The problem statement, all variables and given/known data
L[cos2at]

I know that L[cost] = s/(s2+bs)

I know that cos2at can also be written as 1/2(1+cos2at)

and so I then got the L[1/2]+1/2L[cos2at)]

Which gave me s/(s2+(2a)2)

However this is not correct, there was a + 2at term on the numerator as well.

2. Relevant equations

3. The attempt at a solution

2. Nov 18, 2012

### rock.freak667

L[tn] = n!/sn+1

For L[1/2], n= 0 so you should get 1/2s as that transform.