Square A′B′C′D′ is the image of square ABCD under a dilation from center O1 by scale factor r. Square A′′B′′C′′D′′ is the image of square A′B′C′D′ under a dilation from center O2 by scale factor 14. The side lengths of square A′′B′′C′′D′′ are 18 of the corresponding side lengths of square ABCD. What is the scale factor r?

In a right-angled triangle: 1- the hypotenuse is the longest side2- we can apply pythagorean rule which states that: (hypotenuse)^2 = (side1)^2 + (side2)^2for the given triangle,longest side is 15 cm  side1 = 9 cmside2 is 12 cm  to check whether the triangle is right-angled or not,compare (15)^2 to the summation of (9)^2 and (12)^in other words, compare 225 to the summation of 81 and 144if they are both equal, then the triangle is right-angles, otherwise, it is not.you haven't provided the diagram showing her work, so i cannot tell the choice. however, apply my explanation to the question you have.

Ithink its the 3rd one