Question 3215
 Let the diagonal be d1 and d2
 then the area of the rhombus A = d1*d2 

 Let the side be s, we have (d1/2)^2 + (d2/2)^2 =s^2.

 Hence, the perimeter (of the base)
 = 4s = 2 sqrt((d1)^2 + (d2)^2))


 Kenny