Let AO intersect BC at D
ΔAOB = ΔBOC = ΔAOC (SAS)
AB = BC = AC
ΔABC is equilateral
O is the circumcenter of equilateral ΔABC
Therefore, O is also the centroid of ΔABC
AO / AD = 2/3
2
/ AD = 2/3
AD = 3
![√(3)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/s33jigmx2gpnx3clkmjv4r9kg3iye7ic35.png)
Right triangle ADB has ∠ABD = 60°
AB / AD = 2/
![√(3)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/s33jigmx2gpnx3clkmjv4r9kg3iye7ic35.png)
AB / 3
= 2/
![√(3)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/s33jigmx2gpnx3clkmjv4r9kg3iye7ic35.png)
AB = 6
Perimeter of ΔABC = 6 + 6 + 6 =18