The diagonals of the rhombus are 18cm and 80mm find the perimeter of the rhombus.

By the property of the diagonals of the rhombus, they are halved at the point of intersection.

Then AO = CO = AC / 2 = 80/2 = 40 cm.

BO = DO = BD / 2 = 18/2 = 9 cm.

In a right-angled triangle ABO, according to the Pythagorean theorem, we determine the length of the hypotenuse AB.

AB ^ 2 = AO ^ 2 + BO ^ 2 = 40 ^ 2 + 9 ^ 2 = 1600 + 81 = 1681.

AB = √1681 = 41 cm.

Since all sides of a rhombus are equal, then AB = BC = CD = AD = 41 cm.

Let’s define the perimeter of the rhombus.

Ravsd = 4 * AB = 4 * 41 = 164 cm.

Answer: The perimeter of the rhombus is 164 cm.