Answer:
As mention in the explanation steps.
Step-by-step explanation:
The following expression or phrase to each box are helpful to complete the proof.
(1). We say that ∠ACB and ∠BCD are supplementary, from linear pair of postulate.
(2). ∠ACB + ∠BCD =180°, because ∠ACB and ∠BCD are supplementary (from the difinition of supplementary angles).
(3). ∠ACB +45° = 180° because ∠BCD =45°(substitute).
(4).Subtraction properties of equality ( because we subtract 45 degree from both sides of the previous equation).
(5). ∠ABC is obtuse, because m∠ABC grater than 90°.
(6). From the definition of obtuse triangle (ΔACB is an obtuse triangle because ∠ACB =135 degree which is grater than 90 degree).
