• Choice B

    The points AA, BB, CC, DD, EE lie on the circle with center FF, and EB\overline{EB} is a diameter. The central angles around FF must sum to 360°360°.

    The given central angles are:

    AFB=90°,BFC=18°,CFD=108°\angle AFB = 90°, \quad \angle BFC = 18°, \quad \angle CFD = 108°

    The remaining central angles satisfy:

    DFE+EFA=360°90°18°108°=144°\angle DFE + \angle EFA = 360° - 90° - 18° - 108° = 144°

    The arc DEA\overset{\frown}{DEA} (from DD to EE to AA, not passing through BB or CC) corresponds to the sum of central angles DFE+EFA\angle DFE + \angle EFA:

    DEA=144°\overset{\frown}{DEA} = 144°

    Skills you are tested for:

    Was this explanation helpful?
  • Comments

    To leave a comment,