use the periodic table on page 1839 of you book to fill in the rest of the table. remember you may need to do some addition or subtaction

Using the rise/run rule. you would get 2/6.simp. 1/3

Use pythagorean’s theorem and find the missing side lengths of the two smaller triangles and add them together
13^2 - 12^2 = 5
15^2 - 12^2 = 9
5+9 = 14
14 is the length of each side of the square
14^2 + 14^2 = 19.8
19.8 is the diagonal length of the inside if the square