Answer:
Step-by-step explanation:
As per diagram we have:
- ∠ECA ≅ ∠DCB - vertical angles
- m∠ECA + m∠ABC = 180° - supplementary angles
- m∠ECA = 3x + 5
- m∠ABC = x + 11
Substitute values and solve for x:
- 3x + 5 + x + 11 = 180
- 4x = 164
- x = 41
Find the required angle measure:
- m∠DCB = 3*41° + 5° = 128°
