<s>[INST] $A^2+B^2 +AB=36. B^2+C^2+BC=49. C^2+A^2+AC=64.$ Find $(A+B+C)^2$ 
$$A^2+B^2 +AB=36.\\ B^2+C^2+BC=49.\\ C^2+A^2+AC=64.$$ Find $(A+B+C)^2$.

I have tried it by using geometry I.e constructing a triangle and marking a point inside it which is making 120 ° and then using cosine rule 
But have difficulty in solving further
Please use geometry 
 [/INST] Solution without words
Assume that $A,B,C>0.$

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