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Formula for Perimeter of a Rhombus = 4 x Side or 4S

Step 1. The diagonals of a rhombus bisect one another and create two congruent lines. So the diagonal of 10 units is divided into two five unit lines. 

Step 2. The diagonals create a 30-60-90 triangle.. 

Step 3. In order to find the side of the rhombus, find the hypotenuse of the right triangle. The formula for the hypotenuse of a right triangle equals 2x x = the short leg which is opposite the 30 degree angle.

Step 4. We know x = 5 units from the diagonal being bisected. ( See the picture above) The hypotenuse equals 2*5 = 10 units

Step 5. Now use the perimeter formula of 4s which equals 4* 10 = 40 units

The perimeter is the distance around the outside of an object. A rhombus is similar to a square with a couple of unique features. They are both quadrilaterals with congruent sides but a rhombus doesn't have right angles at the corners like a square.
Step 1. The formula for perimeter of a rhombus equals 4s s = side

Step 2. 4*5= 20 units Perimeter is linear, therefore it is not squared

Perimeter of a Rhombus

Problem 1. What is the perimeter of a rhombus with a side of 5 units? ​

Problem 2. Find the perimeter of a rhombus with a diagonal of 10 units and a m∠ABC=120° ​