This is a question that will require Pythagoras' theorem as you want to find the length of a diagonal of a triangle and are given the measurements of two sides. I have attached a picture of how to solve this problem. To the nearest 10th of a foot, the answer is 77.6ft
Okay we know that tangent-chords creat 90 degree angles so what we have is a right triangle with a base of 9 and a height of 12, so do Pythoagoreas Theorem and we have 81+144=225 square root of 225 is 15 and that is AJ