Question

The perimeter of a right triangle is 18. If the midpoint of these 3 triangles are joined by line segments, they form another triangle. what is the perimeter of this new triangle?

Answer 1

Here's the theorem you need after you sketch the diagram and mark it up:

The segment joining the midpoints of two sides of a triangle has length half that of the third side of the triangle.

Use that theorem three times, and you will see what the perimeter of the inner triangle has to be.