When deriving the distance formula, eowyn starts with two points, a(x1,y1) and b(x2,y2). she then draws point c on a horizontal line from point a and a vertical line from point b, giving it coordinates (x2,y1). in doing so, she believes she created a right triangle, with right angle c, which allows her to use the pythagorean theorem. she lets ac=b and bc=a, which means that ab=c by definition of the hypotenuse.

next, she uses the ruler postulate to state that a=|x2−x1| and b=|y2−y1|. then, combining this information with the pythagorean theorem, she is able to use the substitution property of equality to state that (x2−x1)2+(y2−y1)2=ab2. finally, she applies the square root property of equality to find ab=(x2−x1)2+(y2−y1)2√. she is able to ignore the possible negative root since distance is always positive, by definition.

which statement about eowyn's derivation is the most accurate?