Hiii
The gamma value of every individual number cannot be obtained but can be obtained in terms of gamma value of other number.
So there is an identity used for solving this. which is.
(x) Γ(1-x)=pi/sin(pi x)

from the identity, we can say 
x=1/4
 we get,

Γ(1/4) Γ(3/4)=pi/sin(pi/4)=√2pi

Γ(1/4)=pi√2/ Γ(3/4)


Hope this helps.
Thanks!