Question 1205405
<pre>

Here is a shorter direct proof.  It requires Material Implication

1. C ⊃ (D v A) 
2. A ⊃ H
3. ~H           /~C v D

4. ~C v (D v A)     1, Material Implication
5. (~C v D) v A     4, Association
6. ~A             2,3, Modus Tollens
7. A v (~C v D)     5, Commutation
8. ~C v D         7,6, Disjunctive Syllogism

Edwin</pre>