GIVEN: Perimeter of rhombus = 100 cm Length of its one diagonal = 48 cm CONCEPT: Mensuration FORMULA USED: Side^2= Half of first diagonal^2+ Half of second diagonal^2 CALCULATION: Side of rhombus = 100/4 = 25 cm Length of half of its one diagonal = 48/2 = 24 cm Let the length of its other diagonal = 2a Length of half of its other diagonal = 2a/2 = a cm We know, diagonals of a rhombus are perpendicular to each other. Now, 252=a2+242 ⇒ a2=625–576=49 ⇒ a = 7 cm