Answer:
11) 80°
12) 80°
13) 80°
14) 40°
15) 60°
16) 120°
17) 180°
18) 100°
19) 120°
20) 280°
Explanation:
This will take awhile, so I will just give you the theorems I used to determine my answer.
11) Supplementary angles theorem
12) Central Angles/Arcs Theorem
13) Vertical Angles Theorem
14) Central Angles/Arcs Theorem
15) Vertical Angles Theorem (The vertical angle minus 40 would equal 60)
16) Supplementary Angles Theorem (Supplementary to 100 degrees)
17) Central Angles/Arc Theorem
18) Vertical Angles & Central Angles/Arc Theorem
19) Angle Addition Postulate, somewhat
20) Angle Addition Postulate
Have a nice day, fam. This problem really worked my brain. Spread The Love.