Answer:
[tex]\large \boxed{\sf \ \ 64 \ \ }[/tex]
Step-by-step explanation:
Hello,
[tex]2(a+b+c)=(a+b)+(b+c)+(c+a)=4+5+7=16\\\\\text{*** divide by 2 both sides ***}\\\\(a+b+c)=\dfrac{16}{2}=8 \ \ \text{ so...}\\\\(a+b+c)^2=8^2=\large \boxed{64}[/tex]
Hope this helps.
Do not hesitate if you need further explanation.
Thank you
