Final answer:
Given that S is the midpoint of RT and US equals RT, by definition of the midpoint, triangle STU has two equal sides (US and RT), satisfying the definition of an isosceles triangle.
Step-by-step explanation:
The question addresses the proof of a geometric property using the concept of midpoint and a flowchart proof. To prove that triangle STU is an isosceles triangle, we are given that S is the midpoint of RT and that US equals RT.
Using this information, we can deduce that triangle STU has at least two equal sides, namely US and RT, by the definition of the midpoint, which splits the line segment RT into two equal parts. Consequently, since two sides are equal, triangle STU satisfies the definition of an isosceles triangle, which states that a triangle is isosceles if at least two of its sides are of equal length.
The flowchart proof would start by stating the given information, followed by the definition of the midpoint, leading to the conclusion that two sides of the triangle are equal, ultimately confirming that STU is an isosceles triangle.