The perimeter of the triangle is 19 cm. Find the unknown side of the triangle 5 cm and 6 cm.

So, from the condition we know that the perimeter of the triangle is 19 cm.In order to find the unknown side of the triangle, if the known two other sides of it are 5 cm and 6 cm, recall the formula for finding the perimeter of the triangle and compose and solve the equation.

So, the perimeter is the sum of the lengths of all sides of the triangle.

P = a + b + c;

Let us denote by x cm the length of the third side of the triangle and compose the equation:

x + 5 + 6 = 19;

x + 11 = 19;

We are looking for an unknown term:

x = 19 – 11;

x = 8 cm length of the third side of the triangle.