Answer:
- a) 60°
- b) 80°
- c) 100°
- d) 50°
- e) 30°
Explanation:
The key here is that AB ║ EC. This makes arc AE have the same measure as arc BC. Since those have the same measure as AB and the three arcs together make a semicircle, each has measure 180°/3 = 60°.
Then the various arc measures are:
- AB = 60°
- BC = 60°
- CD = 80° (given)
- DE = 100° . . . . . since CDE is 180°
- EA = 60°
Then your answers are ...
a) AE = 60°
b) ∠ABD = (1/2)(DE +EA) = (1/2)(100° +60°) = 80°
c) ∠DFC = (1/2)(CD +EB) = (1/2)(80° + (60° +60°)) = 100°
d) ∠P = (1/2)(DA -AB) = (1/2)(100° +60° -60°) = 50°
e) ∠PAB = (1/2)(AB) = (1/2)(60°) = 30°