Henry cuts a large triangle into three congruent triangles. Then he puts them together as shown. Three identical triangles are positioned so that they each share at least one side with another triangle and form a trapezoid. The three congruent triangles make a straight line across the bottom. Which geometric fact did Henry illustrate? A The sum of the measurements of the angles of a triangle always equals one hundred eighty degrees. B The angle of a triangle with the smallest measure is opposite the shortest side. C No more than one angle in a triangle can have a measurement greater than ninety degrees. D The length of any side of a triangle is shorter than the sum of the other two sides.