Vertical angles are always congruent and share the same vertex. They can be either acute, obtuse, or right angles, but are not necessarily complementary. Therefore, the properties that apply to vertical angles are A and D. ;
Vertical angles are always congruent and they share the same vertex where two lines intersect. They can be any type of angle (acute, obtuse, or right) but are not necessarily complementary. Therefore, the applicable options are A and D.
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