4. Using the first two statements in the proof fragment below, state the reason for writing the third statement in the proof. W 1 2 2 mZ1 = m 23 given m/DB. A= m23+m2 Angle addition postulate MZDB.4 = m Z1 + Z2 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

36.75 because 21/4 = 5.25 and 36.75/7 = 5.25