Question

Find the value of L{cos(at + b)}​

Answer 1

Answer:

we know that cos(m+n)=cos(m) cos(n)- sin (m) sin(n)

L{cos(at+b)}=L{cos(at) cos(b) - sin(at) sin(b)}

=cos(b) L{(cosat)} - sin(b)

=cos(b) s/(s^2+a^2) -

L{sin(at)}

sin(b) a/(s^2+a^2)

In the above steps denominators are same hence we get

= {s cos(b) - a sin (b)}/

(a^2+s^2)