You can put this solution on YOUR website! A = [(a^2)/4]sqrt(3)
153 = [(a^2)/4]sqrt(3)
153/sqrt(3) = (a^2)/4
4[153/sqrt(3)] = a^2
sqrt{4[153/sqrt(3)]}=a
Perimeter is just three sides adding together; and since all the sides are the same we can take one side times 3
3sqrt{4[153/sqrt(3)]} = P = 56.392 cm