Question

A and B are vertical angles. If m_A = (3x – 9° and m B = (x + 3)º,then find the value of x.

Answer 1

Given:

m∠A = (3x - 9)

m∠B = (x + 3)

A and B are vertical angles.

Vertical angles are always congruent.

Thus,

m∠A = m∠B

3x - 9 = x + 3

Let's solve for x.

Add 9 to both sides:

3x - 9 + 9 = x + 3 + 9

3x = x + 12

Subtract x from both sides:

3x - x = x - x + 12

2x = 12

Divide both sides by 2:

`\begin{gathered} (2x)/(2)=(12)/(2) \\ \\ x\text{ = 6} \end{gathered}`

ANSWER:

x = 6