peri,meter = 12

semiperimeter(s) = 12/2 =6

now side = 12/3= 4[as it is equilateral triangle all the side will be equal]

now area of triangle = sqr(s*(s-a)*(s-b)*(s-c)) = sqr(6*(6-4)*(6-4)*(6-4)) = 6.93