The perimeter of the triangle BMP is 128mm and it is known that the side of the BM is 5 cm 6 mm, and the side of the MP

The perimeter of the triangle BMP is 128mm and it is known that the side of the BM is 5 cm 6 mm, and the side of the MP is half the length of the BM. Determine the length of the BP side.

We need to determine the length of the side of the triangle BP.
From the condition of this problem, we know the value of the perimeter of the triangle under consideration. We know that the perimeter of a triangle is found as the sum of the lengths of all its sides. By condition, we have a BMP triangle, therefore, its perimeter is calculated as:
P = BM + MP + BP
But according to the condition of the problem, we know the following:
P = 128 mm;
BM = 5 cm 6 mm = 5 * 10 + 6 = 50 + 6 = 56 mm;
MP = BM / 2 = 56/2 = 28 mm.
Then:
128 = 56 + 28 + BP
Hence:
BP = 128 – 56 – 28 = 44 mm = 4 cm 4 mm