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)
Responses
x = 30
x = 30
x = 60
x = 60
x = -18
x = -18
x = -9
Since vertical angles are congruent, we have:
m∠AOC = m∠BOD
21° = (2x + 39)°
Subtracting 39° from both sides, we get:
21° - 39° = 2x°
-18° = 2x°
Dividing both sides by 2, we have:
-9° = x°
Therefore, the value of x is x = -9.