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? (2 points)
Since ∠AOC and ∠BOD are vertical angles, they are equal. Therefore, we have:
21° = (2x + 39)°
Subtract 39 from both sides:
21° - 39° = 2x° + 39° - 39°
-18° = 2x°
Divide both sides by 2:
-9° = x
Therefore, the value of x is -9.