C.
have the same vertex.
done
D.
be congruent
not all congruent angles are vertical angles. Vertical angles must share a vertex.
Vertical angles must be congruent so if they are complementary, they must be 45 degrees to be complementary.
No.
Equal angles.
Vertical, possibly!
Vertical angles must necessarily be congruent, however congruent angles do not necessarily have to be vertical angles. An example of congruent angles which are not vertical angles are the 3 interior angles of an equilateral triangle. These angles do not share the same vertex yet they are congruent.
Equal angles.
have the same vertex. be congruent.
Vertical angles are formed when two lines intersect, creating two pairs of opposite angles. These angles are always equal in measure; therefore, if one angle measures 50 degrees, its vertical angle will also measure 50 degrees. This property is a fundamental concept in geometry and is useful for solving various problems involving angles.
Because if they werent, they would eventually form an angle.
they can be obtuse say ther are two lines intersecting two of the angles are acute (50degrees) that means the other pair must be obtuse 180-50=130 so the other two angles are obtuse with a measurement of 130degrees
Angles that are congruent and supplementary must be right angles.