Respuesta :

KiaraL2006

Answer:

18.0 cm

Step-by-step explanation:

use the cosine rule:

a^2=b^2+c^2-2bcCos(A)

a^2=10.4^2+10.4^2-2x10.4x10.4Cos(120)

a^2=324.48

a=sqrt(324.48)

a=18.0cm (1dp)

hope this helps :)