For a triangle with sides a, b and c, the perimeter P is defined as: P = a + b + c. What this formula means in simpler terms is that to find the perimeter of a triangle, you just add together the lengths of each of its 3 sides. In this example, the length of side a = 5, the length of side b = 5, and the length of side c = 5. This particular example is called an equilateral triangle, because all three sides are of equal length.  But remember that the perimeter formula is the same for any kind of triangle. In this example, 5 + 5 + 5 = 15.  Therefore, P = 15. In another example, where a = 4, b = 3, and c=5, the perimeter would be: P = 3 + 4 + 5, or 12. If the sides of the triangle are measured in centimeters, then your answer should also be in centimeters.  If the sides are measured in terms of a variable like x, your answer should also be in terms of x. In this example, the side lengths are each 5cm, so the correct value for the perimeter is 15cm.

How would you rephrase that briefly using Indonesian?
Ingat kembali rumus untuk mencari keliling. Perhatikan segitigamu dan tentukan panjang ketiga sisinya. Jumlahkan panjang ketiga sisinya untuk mencari keliling segitiga. Selalu tambahkan satuan ke dalam jawaban akhir.