Answer:
317°
Step-by-step explanation:
The total measure of the angles around the center of the circle is 360°. The sum of angles in each half (above AB or below AB) is half that, or 180°. So, the sum of angles below the line is 180°. We can use that fact to find x, then the measures of all of the angles.
(7x +1)° +90° +(9x -7)° = 180°
16x = 96 . . . . . divide by °, subtract 84
x = 6 . . . . . . . . divide by 16
Then angle AOD is ...
(7·6 +1)° = 43°
Short arc AD is 43°, so long arc ACD is 360° -43° = 317°.
arc ACD = 317°
