الجبر Question in extension fields

[hanin]

Hello all;
I need ur help in the following question plz:


let a,b be two algebriac over K , [k(a):K]= m , [k(b):b]= n ,gcd(m,n)=1 , show that [k(a,b):k]= mn
Thanks in advance for any help

 

[hanin]

I need ur help plz!!!!!!!!!!!!