Find the perimeter of a rhombus the length of whose diagonals are 10 cm and 24 m.

check the picture below.

recall that in a rhombus, both diagonals bisect each other, namely cut each other in equal halves and at right-angles, so we end up with 4 right-triangles.

now, the sides in a rhombus are all equal, thus the perimeter is 13+13+13+13.

54/3 is 18 so 18 is your answer