In the above figure, m∠AOC = 21° and m∠BOD = (2x + 39)°.
If ∠AOC and ∠BOD are vertical angles, what is the value of x?
If ∠AOC and ∠BOD are vertical angles, then they are congruent.
Thus,
21° = (2x + 39)°
Subtracting 39 from both sides, we get:
-18° = 2x
Dividing by 2, we get:
x = -9
Therefore, the value of x is -9.