PA is a tangent, PBC is a secant, AOC is a diameter, AD and DC are chords
Angle APC = 57, Angle DC = 34
<em>[measurements are in degrees]</em>
(A) Arc BA = 66
Since AOC is a diameter, Arc AC is 180. Angle APC is equal to half the difference between BA and AC.
APC = 1/2 (AC - BA)
57 = 1/2 (180 - BA)
114 = 180 - BA
BA = 66
(B) Arc BD = 80
BD is 360 minus BA, AC, and DC.
BD = 360 - BA - AC - DC
BD = 360 - 180 - 66 - 34
BD = 80
(C) Angle ACD = 73
ACD is half of ABD, which is BA plus BD.
ACD = 1/2 (BA + BD)
ACD = 1/2 (66 + 80)
ACD = 1/2 * 146
ACD = 73
(D) Angle BED = 130
BED is the same as AEC, which is 180 minus ECA and EAC.
ECA is half BA, and EAC is half DC.
BED = 180 - 1/2 BA - 1/2 DC
BED = 180 - 1/2 * 66 - 1/2 * 34
BED = 180 - 33 - 17
BED = 130
(E) Angle PCA = 33
PCA is half BA
PCA = 1/2 BA
PCA = 1/2 * 66
PCA = 33
(F) Angle PAD = 73
PAD is half ABD, which is BA plus BD.
PAD = 1/2 (BA + BD)
PAD = 1/2 (66 + 80)
PAD = 1/2 * 146
PAD = 73
