The perimeter of the triangle ABC is 19.3 cm. AC = 7.9 cm. The AB side is 2 times shorter than the BC side. Find the BC side.

We will assume that the side of triangle AB is equal to x, then the side of BC will be (2 * x). The perimeter is equal to the sum of the three sides, it is 19.3 cm.We get the equation:
x + 2 * x + 7.9 = 19.3;
3 * x = 11.4;
x = 11.4 / 3;
x = 3.8 cm – the length of the side AB.

Determine the length of the side BC:
BC = 2 * x = 2 * 3.8 = 7.6 cm.

Examination:
3.8 + 7.6 + 7.9 = 19.3.

Answer: The side of triangle BC is 7.6 centimeters.