Answer:
m∠7 = 63 degrees
m∠8 = 117 degrees
m∠9 = 63 degrees
Explanation:
When two lines intersect at a point, then they formed 2 pairs of vertically opposite angles and 4 pairs of linear angles
- The vertically opposite angles are equal in measures
- The linear angles have a sum of 180°
In the given figure
∵ There are two lines intersected at a point
∴ The angle of measure 117° and ∠8 are vertically opposite angles
∴ ∠7 and ∠9 are vertically opposite angles
∴ The angle of measure 117° and ∠7 are linear angles
∵ The vertically opposite angles are equal in measures
∴ The angle of measure 117° and ∠8 are equal in measures
∴ m∠8 = 117°
∵ The sum of the measures of the linear angles is 180°
∴ m∠7 + 117° = 180°
→ Subtract 118 from both sides
∵ m∠7 + 117 - 117 = 180 - 117
∴ m∠7 = 63°
∵ m∠7 = m∠9 ⇒ proved up
∴ m∠9 = 63°