Given a triangle with sides 3: 4: 5, perimeter = 36. Find the middle lines.

Knowing that the sides of this triangle are related as 3: 4: 5, and its perimeter is 36, we can write the equation:

3x + 4x + 5x = 36;

12x = 36;

x = 36/12 = 3.

Therefore, the sides of the triangle are equal:

a = 3 * x = 3 * 3 = 9;

b = 4 * x = 4 * 3 = 12;

c = 5 * x = 5 * 3 = 15.

It is known that the middle line of a triangle is equal to half of the side to which it is parallel. Find the middle of the line:

ma = a / 2 = 9/2 = 4.5;

mb = b / 2 = 12/2 = 6;

mc = c / 2 = 15/2 = 7.5.