The statement that could be proved with the help of the figure is "A line connecting the midpoints of two sides of a triangle is parallel to the third side and half its length."
This statement involves a specific geometric property that can be illustrated with a figure showing a triangle and its midpoints. The proof typically involves demonstrating that the segment connecting the midpoints is parallel to the base and showing that its length is half of the base through properties of similar triangles.
The other statements, while also true, are more general geometric theorems that typically require separate proofs not reliant solely on a figure illustrating a single triangle.