What is the perimeter of a rhombus whose area is 30 square cm and whose largest diagonal is 12 cm showing work?

Let the other diagonal be x

If: 0.5*12*x = 30 then x = 60/12 => x = 5

The rhombus has four interior right angle triangles with lengths of 6 cm and 2.5 cm

Using Pythagoras each equal sides of the rhombus works out as 6.5 cm

Perimeter: 4*6.5 = 26 cm