Given: Angle1 and Angle2 are supplements, and Angle3 and Angle2 are supplements. Prove: Angle1 Is-congruent-to Angle3 Three sepa
rate angles are shown. They are labeled 1, 2, 3 from left to right. Complete the missing parts of the paragraph proof. By the definition of supplementary angles, the sum of the measures of angles 1 and 2 is 180 degrees. Likewise, the sum of the measures of angles 3 and 1 is 180 degrees. By the substitution property, mAngle1 + mAngle2 = mAngle3 + mAngle2. Subtract the measure of angle from each side. You get mAngle1 = mAngle3, or Angle1 Is-congruent-to Angle3, by the definition of congruence.
