Vertical angles must: . check all that apply . a. be a linear pair. b. have the same vertex. c. be adjacent . d. be congruent.

Vertical angles must have same vertex and be congruent.

Step-by-step explanation:

When two lines crosses each other , the opposite angles are known as vertically opposite angles or vertical angles where "vertical" refers to the vertex .

Also we know that Vertical angles theorem says that vertical angles are always congruent.

Therefore,  Vertical angles must have same vertex and be congruent.

answer: i'm not going to give you the answer, but some hints to work it out.

step-by-step explanation: so, if there is a straight line that means that the line angle is 180°. so we subtract the 2 angle measures provided, (15 and 38) from 180. so the answer is 180 - (38 + 15). (you have to solve the equation)