if WX || YZ, then ∠WXZ and ∠XZY are supplementary

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• ∠WXZ and ∠XZY are supplementary, if (WX || YZ) and (m∠WSX = 180) and (m∠YTZ = 180), then ∠WST and ∠STY are supplementary
  • WI || YJ, if (AB || XY) and (m∠ABC = 180) and (m∠XYZ = 180), then AC || XZ
    • WX || YZ
    • m∠WXI = 180
    • m∠YZJ = 180
  • m∠WXI = 180
  • m∠YZJ = 180