Let the base of square and rhombus be a units . Square all sides equal ;;; Area of square=a^2;;

let the height of rhombus , i.e perpendicular distance from the top edge to the base be h units and included angle be x

then area of rhombus =a*h=a^2sinx

ratio = (a^2)/(a^2*sinx) === 1/sinx and since 0<x<90 ;; 0<sinx<1;;; the ratio will always be greater than 1 ,,,,