c=9, α=40°, β=20°
а-?, b-?, γ-?

γ=180-(40+20)=120
По т. синусов:
a/sinα=b/sinβ=c/sinγ
a=c*sinα/sinγ=9*0.64*2/√3=6.68
b=c*sinβ/sinγ=9*0.34*2/√3=3.55