Select from the drop-down menus to correctly complete the statements. By the triangle sum property, the sum of the measures of angles 2, 3, and 4 is 180 °. The sum of the measures of angles 1 and 4 is 180° because they are vertical . Using the substitution property, m∠2+m∠3+m∠4=m∠1+m∠4. Then, m∠2+m∠3=m∠1 by the subtraction property of equality . Triangle oriented so a vertex is at the top and center. This angle is labeled 2. The angles at the base of the triangle are labeled 3 and 4, where 3 is the left bottom angle and 4 is the right bottom angle. The base is extended to the right, and the angle outside of the triangle, adjacent to angle 4, is labeled angle 1.